Time machine running forever

I think it is time machine running on my external drive and I want to terminate the process without causing file system pointer problems which can be experienced with interrupting TM and which I have already experienced.

On my TM Volume I have the following under the latest backup folder:

It's the InProgress entry I'm concerned about. I don't know what to look for in the ps output to kill the process. Plus I don't want to damage file system that has happened to me in the past.

I really don't want any of the old backups as they are the old Mac filesystem anyway.

I want to stop the process without damaging anything, delete all the old files and start over.

This volume is being used for other storage as well, so wiping the whole volume clean is not an option. Will Disk Utility all me to wipe part of the volume?

Using High Sierra. Yes, I know. After I get a good backup, I will upgrade.