I am building a skill that needs a toggle. When active you will have a stat altered slightly, and when inactive it returns to normal. In this particular case the ability calls for a -1 to intelligence. So the goal is you turn it on as an action (or out of combat) and then the stat change happens, but if you turn it off you clear the stat change and go back to normal. So far I have not been able to figure out how to do it. I can make the stat penalty exist, but it's an always on kind of thing and I would like to be able to toggle it at will as a reminder that the effect is active.

I do not know if it is even doable in DNDBeyond, but I'm hoping if it can be done, someone will know how to do it.

There's no way to create a toggle. The closest is a homebrew magic item - to toggle on you equip it, to toggle off you unequip. I usually set them to Artifact rarity so they appear at the top of the inventory for quick access. I use them for things like Haste and Mage Armour, and such effects. 

Ooo this is interesting. This might work better than a feat. Can you set a stat penalty as an equip effect on an artifact?

EDIT: It absolutely can. Just gotta set a negative bonus. Works perfectly, thank you very much for the suggestion!