I want to switch iPad to new apple I'd account

You can log out of the currently logged in account on the iPad by tapping on the id in Settings > Settings > iTunes & App Stores, and you then log in with a different account. Any content that was downloaded via the currently logged in account will remain tied to that account, so only that account will be able to re-download it and download updates to its apps.

Also, using iTunes Match with an account, turning on automatic downloads or re-downloading an account's past purchases amy tie a device (or computer) to an account for 90 days : http://support.apple.com/kb/HT4627