Deleting Time Machine Backups

I have a 1TB iMac (late 2015) running Big Sur OS. I use Time Machine to backup to a 2TB external hard drive. Recently I got a message "Time Machine could not back up the disk "Macintosh HD - Data" because it is nearly full. Delete some files on this disk and try again." I assumed "it" meant the external HD but my Mac HD is nearly full as well. I went into Finder and opened the external HD and proceeded to select some of the oldest backups and move them to trash. Emptied trash. Still had message about not enough room so moved more backups to trash. It's been trying to empty the trash for hours (overnight). I got a few messages about some things being in use so I hit Continue/Skip/Stop (chose each one along the way hoping it would either finish or just stop trying) but it is still going with the delete. After doing some reading I'm realizing deleting using Finder was prob a bad idea as the backups build on one another (only changes are backed up). It didn't seem like that was the case because in opening an older backup, I could see the same document as in a newer backup and the doc hadn't changed between the two so figured I was safe. Anyways, my two questions are as follows:

1. Is there a way to stop the trash from trying to empty itself or get it to complete the emptying of these backup files?
2. How do I delete my external HD and start over with Time Machine? At this point I just want to start over with a complete backup since I may have messed them up by deleting some backups and I really don't ever intend to restore a backup from a random week one year ago. I really just want to make sure I have a recent backup or two available.

Thanks!