Can one really 'lose' old bad grades and get a fresh start?
That's not necessarily the impediment you may think.  The institution where I taught would not accept nor transfer credit over ten years old.  Pick one or two colleges you might attend, visit their admissions offices, and ask.  There's a good chance you can start fresh.

There are two things to keep in mind.  Your transcript from your old institution will still be there, and you will be asked for it when you apply for any degree program.  It may lessen your chances of admission, but probably not because fifteen years is a long time.

The other is that you should be honest about your education history on your resume.  Once again, fifteen years is a long time.  Do well now and no employer will even consider that ancient history.

Go for it!