Is there a way to deactivate a member's account? We want deactivate accounts when users cancel their subscription with us and reenable them when users reopen their subscription, this way all their previous data is preserved.

There is no "deactivate" button, but I've done this myself in the past. Just create a new group and remove all permissions from it called deactivated. Then you can move members to that group.

Nice tip!

There’s a 3rd-party resource to deactivate accounts: