How do I erase prior Time Machine archives as a means to restarting a new Time Machine archive after a long hiatus from using Time Machine?

Used Time Machine from 2012 to Nov 1014 and ceased thereafter to the present. Purchasing an Apple Time Capsule (5th Gen 2TB) and want to purge prior Time Machine archives as a precursor to beginning to renew use of time machine to use the storage capacity of the Apple Time Capsule. I have only backups of the iMac Desktop visible in Time Machine and the "Delete all Backups of "Desktop" will not perform the deletion. Question: How can I do the purge of Time Machine Storage files before restarting a Time Machine Restart?