Sounds misaligned, why would you agree to mentor people if you don't want to do that? Alternatively, if you want to mentor people, why would you decline their requests for meeting them?

Here's some ideas, many of which I wouldn't do myself:

* Find them other mentors for particular problems. This isn't passing the buck, sometimes there are more appropriate mentors for their problems.

* Ask them if any of it can be done async

* Suggest less frequent 1:1s

* Batch 1:1s so its less disruptive to you.

* Its chaotic evil but Don't provide useful advice. They will eventually stop wasting their own time.