On my PC I have TSW 4,5,6 and now the free edition of V7 Does each update download and install all my route and stock files separately. Is it safe to delete the old versions of TSW using the Windows uninstall option. Paul
Yes, you can safely delete the old ones. Be sure not touching old TSW folders in documents before you import your profile.
Psuedostalker is correct but you may also want to preserve the screenshots/photo mode shots that you took by finding their folder locations before deleting the files in 'Documents'. Unless you have those saved to Steam or elsewhere - then you needn't worry.
A caveat is that if you have the Peninsula Corridor route and Caltrain locos, you might want to keep the TSW5 versions as they're branded, whereas the TSW6 onwards versions aren't. Depends on how important that is to you.
He's on PC, and there's an excellent mod that recreates the SFJ branding exactly as it was in TSW 5, if not even better.