I'm trying to effectively create a magic weapon that anyone can pick up and use, even if not trained. is it possible to remove the following line and have everyone who equips it count as proficient?

Proficiency with a shortsword allows you to add your proficiency bonus to the attack roll for any attack you make with it

You can try making the weapon grant proficiency in that weapon type.

it didn't remove or change that line of text, but it did grant the proficiency, thank you. I can live with that

There is no way to remove that line of text. You can also use weapons you aren't proficient with, you just have a lower hit mod.