You can delete old availability entries individually through the Availabilities feature. At this time, Team App does notoffer a bulk delete option for availabilities.
Steps to Delete Old Availabilities
Go to the Availabilities tab on your home screen
Select an old availability you wish to remove
Tap the three dots (⋮) in the top-right corner
Select Delete
The availability entry will be removed from your app
Important Notes
Bulk delete is not currently supported — each availability must be deleted one by one
Deleting an availability removes it from all members’ views
Once deleted, the entry cannot be restored