How to configure auto deletion of source branch after merge by user and/or branch prefix?

[Jia Yin LIM]

As per title. To give more context, here's my use case:

One of us handles daily releases where PRs are created, and we want to keep them. It's a big problem if the source branch is deleted.

The rest of us work with fixes/features and we want source branches deleted after merging the PR. Like everyone else, it's not a big deal but it leaves a lot of stale branches if some of us forget to clean up.

The browser cache was very handy but recently(?) removed -- I'm wondering if there's a feature unknown to me to achieve similar.