There are a couple of options, depending on what method you are using to
update the table.
If you are using direct table entry, even with a form front-end, you can hit
the Esc key.
If you are using unbound fields, and then running an Insert command, simply
reset the fields to "". I find a Cancel button is very easily understood by
users.
There is also a Rollback statement, or something like it, that can be used
in code. I've never used it, but I did see it posted sometime last week.
Maybe someone can offer it here.
Good luck.
Sharkbyte