Hi Todd,
Open a new blank document. Then go to Insert > File and point to the old
document. You should get the form without the protection. Save this new
document with a different filename. If you want, you can then delete the old
document and rename the new one.
Yes, you could just save the new one to the same name and overwrite the old
document. But years of mistakes, crashes, and gremlins have taught me never
to get rid of the one-and-only original until the copy is safely stored and
checked for viability. The more you're pressed for time, the more important
this caution becomes because the probability of a mistake increases.
For the future, if a form is important, save a copy without a password in an
archive folder, and password-protect only the one you send out to others. If
you're really paranoid, also store that password in the archive folder, in a
text file sharing the base name of the form document.