I'm using Time Machine. Its Full. Deleting older backups as it goes. My desktop Mini is full. I want to delete all files on my computer. How will this affect Time Machine?

I'm really wanting to make room on my Mac Mini. I have about 70 gb left. I'm not sure what to do. I'm using Time Machine to regularly backup my computer and its already full and deleting older backups. I used to, in the past before Time Machine, just drag and drop files into an external hard drive and empty the file from my computer. Should I follow a similar procedure here? If I have time machine backup up, and I remove all my files from the computer, will Time Machine begin to backup a "clean" machine onto the external drive and begin deleting past backups? What would be the best way to approach my backups, remove all my files from my computer since a variation of them are already on time machine, and not lose viable backups? Thank you.