how i can disable my ipad

You really wish to disable it? Or is it disabled and you want to get it working again? If the latter:

Read this Apple Support document about what to do "If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled". Click here --> http://support.apple.com/HT204306

If the former:

Find My iPhone: Lock and track your device using Lost Mode - https://support.apple.com/kb/ph19299?locale=en_US