There are no .dwl files under .bak. I save all the files to Google cloud.
So what do I delete before opening TC again?
A .dwl file is a temporary file created when one opens a TC drawing, it is normally created in the same folder as the TC file is opened from, but I don't know if this still applies to the cloud (I would think it does), when a file is opened a dwl is created to keep track of who has opened the file, and help prevent two people opening and editing the file at the same time, which would cause problems and possible corruption. The dwl file is normally deleted automatically by TC when the program closes. If TC crashes, the dwl can be left behind.
Check if you have any dwl files in the same folder (or cloud) you normally open / save tc files to. they will not normally appear in the Bak (backup) folder.
If you are using the cloud, I'd keep an eye on the bak folder, as any interruption in connection to the cloud has the potential to corrupt your file. so the Bak folder will be valuable. Under options menu - Desktop, Save/open, there is 'make backup copies', I have mine set to Backup on every save, it may slow saving a touch on large files, but well worth it..
As for ASV / CRS, autosave files are automatically deleted by TC when it closes, except, in certain circumstances where TC closes unexpectedly, like a power cut, or some other unexpected closures. In those instances the ASV file may survive. A CRS or crash file is only created (I think) when TC encounters a problem that can be handled by TC's internal error handling programming.