I’ve noticed that there is no longer a button or link to delete a registered application ( twitch.tv/settings/connections ). Is/was this/that intentional? If so what is/was the reason behind it and will we get it back?

There has never been an option to delete a registered application.

Delete Registered Applications

Topic		Replies	Views
Delete registered app API	2	1920	September 19, 2016
New Twitch Application error API	1	877	June 23, 2014
Application missing from the list API	1	216	May 19, 2022
App management is now a part of dev.twitch.tv Announcements	0	3202	August 30, 2017
Where can you edit developer applications? API	6	1953	January 3, 2016