hello, this one is very tricky :) no direct link :)
from copilot studio connexion screen you canno't delete , i suppose you try also to go there
and then try here
But
if you wan't to permanent suppress connexion you need to go in the connexion management tool of you'r environnement.
Bad news : no direct link from copilot studio, you have to bounce from another tool like power apps to see the connexion tool
so look closer at the environnement you are in copilot studio
Remind this exact name, then go to another tool of the power platform, like power apps, do like this
then go to connexion tool BUT verify at right top you are still in the same environnement as in copilot studio (at the begining) : very often when you switch tool, you will be drop in another environnement
and then you will have the delete button
I hope this help to resolve :) if yes please click on the good answer to change the post in green, it's important for the community and the search engine :)
