Can I delete Volunteers after the PiT event?

Sort of.

You can delete users with the PiT Volunteer role if there’s no data attached to them.  In other words, if they don’t show up for the PiT Count and don’t complete any surveys, you can delete their account.

Update: In HIFIS version 4.0.55.12, the ability to delete volunteers was temporarily removed

You can’t delete users that don’t have the PiT Volunteer role.

You can’t delete users that have data attached to them. In other words, if the user has completed a PiT Count survey, they can no longer be deleted.

You can’t delete people, at all.

You can, however, make users and people inactive. Inactive People can’t be selected, and inactive users can’t log in.