When adding a reminder I can select "Custom" and choose a
non-default reminder time. This time gets added to the list of
reminder times, which is usually a great idea. But sometimes
there's a need for a weird very specific reminder time, and it's
rather silly to see, say, "3 hours 18 minutes" in the list of
reminder times forever from now on.

Would be good if, say, long press on a custom reminder time (or, even better, any reminder time) would open a popup asking to delete it.

A companion feature would be to have a menu item in Settings->Reminders to "Reset reminder times", which would delete all custom reminder times (and restore deleted default reminder times, if one would be able to delete them).

(there's a very similar suggestion 8880247, which is marked completed but doesn't seem to be actually implemented, so I'm submitting this again)