You should be able to just mirror what you're already doing. Add a button for "delete" in your form, when you're processing the data from the forum in the PHP script, check the value of the submit, if its "delete" then ignore everything else and run the delete script.
I wouldn't say the iPhone instructions aren't helpful, just maybe a bit misleading since its the only device listed, and maybe a bit sparse since there could be screenshots of the iPhone and more PPTP devices could also be interesting. Also, the configuration process might change in a future iPhone version - never know. Just a link to a wiki page would do it - move the iPhone instructions there. Then everyone gets the most up to date information all the time.
Sorry, I guess I'm not up on the PPTP spec... Thanks for the correction.