Hopefully a real solution will be offered, but for a workaround they could just replace the monsters in the encounter they were going to delete

Encounter Builder isn't shared under the master tier, so the 8 limit is what the player in your campaign is left with.  Master Tier allows you to share source books and I think homebrew, but not tools.

A quick search of "delete encounter" in this forum seems the simplest solution is to reset the encounter and delete the ones they have.  If that fails, this is an extensive thread on getting encounters deleted when the deletion proves problematic:

https://www.dndbeyond.com/forums/d-d-beyond-general/bugs-support/116577-cant-delete-encounter-in-encounter-builder

I also have this problem: I can't edit or delete two encounters no matter what I try. They've been stuck on my list for a while. I cannot be certain, but the campaign was inactive for a while, which might be part of the problem? I have reactivated the campaign but I still can't do anything with them. The encounters have a title in my encounter list, but when I click on them, they come up as Untitled Encounter, with last save in 1969, and "making a perception check to find the encounter..." Clicking on the edit option via the right side menu just brings up the page for creating a new encounter (no encounter name, standard preset party, no monsters). Here are links: 

https://www.dndbeyond.com/encounters/a43421bd-b64d-468a-b94d-f1ffe0fc34e6

https://www.dndbeyond.com/encounters/bbfaeb51-234a-4685-a70c-3fd34ef91146

Same issue for me also.

Please see this post earlier in the thread.  

Quote from Sorce >>

The issue can fall into two categories.

1 - The encounter does not have a name (so is called Untitled Encounter). To resolve this, name the encounter, and then it should delete. (0.00001% of the time an unnamed encounter can fall into category 2)

2 - The encounter does have a name and cannot be deleted. To resolve this, you will need to raise a Support Ticket, as we need the dev team to run the rebuild tool on these encounters. 
When raising a Support Ticket (http://dndbeyond.link/SubmitTicket), be sure to select in the form that the issue is related to Encounter Builder, include your Username/Nickname and please include the Name(s) of the encounter and the URL(s).

 
I just performed a (successful) test of a theory I had using the following steps:

• Created a campaign to test my theory.
• Took an old encounter I used to test rollables for a few monsters I ‘brewed up that had not previously been assigned to a campaign, and assigned the encounter to that theory test campaign.
• When notified that there were no characters in that campaign I had the encounter builder add to dummy 1st level generics and saved the encounter.
• Deleted my theory testing campaign.
• Created 2nd theory testing campaign with a slightly different name.
• Edited the relevant encounter to assign it to the new, second theory testing campaign.
• When notified that there were no characters in that campaign I had the encounter builder add to dummy 1st level generics and saved the encounter.
• Navigated back to My Encounters.
• Successfully deleted the encounter.

🤷‍♂️

I have another one...  It's an encounter called Winter One-Shot that I can not delete.

Quote from MaelstromDelScorcho >>

I have another one...  It's an encounter called Winter One-Shot that I can not delete.

 Well then, try the advice in the two posts directly above yours.

I have one encounter that I deleted but continues to show up in the list. Clicking on it take me to an "Untitled Encounter" with an empty stage.

https://www.dndbeyond.com/encounters/cdcb21a5-98e7-49f5-adfb-02eb597f8923

Running the Encounter just shows an empty encounter.

Untitled Encounter
Last save was on December 31, 1969 at 4:00 PM

Trying to delete from the menu on this screen generates the pop-up:
Are you sure you want to delete Untitled Encounter (created December 31, 1969)? There is no undoing this.

But nothing happens.

Have you seen this?

https://www.dndbeyond.com/forums/d-d-beyond-general/bugs-support/116577-cant-delete-encounter-in-encounter-builder?comment=71

Thanks all - it does have a name and I am unable to edit the named encounter. I'll raise a ticket with Support.

For reference, console msg:

errors: {message: ["Encounter does not exist"]}
status: 401
title: "One or more errors occurred."
type: "EncounterNotFoundException"

Root cause? I was able to delete such an encounter for myself without having to raise a support ticket. I was pointing out that I had discovered a way to do it without support so it could be independently tested and verified.

I've noticed that this bug appears frequently when you try to delete encounters that are currently running.

Last year I made an encounter for one of my campaigns in the encounter creator.  I ran the encounter, it was fun, the party gained xp.  The name of the encounter is 'Snake in Grove' if it matters.  I'll give you one guess about what the encounter consisted of.

Anyways, now I want to delete the encounter, but I can't.  Selecting (...) and then Delete on the My Encounters page (and then selecting 'confirm') doesn't do anything at all.  Moreover, I can't click on the encounter to see any details either.  It just stays on "Making a Wisdom (Perception) check to find the encounter..." forever.

Since this is using one of my limited encounter slots, I'd really like this thing deleted (yes, I happen to have a sub right now, but I won't forever).  Has anyone had this issue?  If so, how did you fix it?  Can any DnDBeyond admins or tech people help me?  Thanks!

Post the link to the encounter so a staff member can take a look.

Quote from naruhoodie >>

Post the link to the encounter so a staff member can take a look.

 Okay.  Here it is:

https://www.dndbeyond.com/encounters/207f982b-9437-454c-8476-ed4c7be44bf9

Ironically a moment after posting this thread I noticed that another encounter is broken as well.  This one:

https://www.dndbeyond.com/encounters/b3eb5b86-e968-4f43-8c8e-73f7666b7e72