Erasing an old iPad Air 2. How do I erase all for disposal without affecting other apps thru iCloud?

My old iPad Air 2 has lost its photo display ability (all pictures are displayed in weird psychedelic colors. I haven't used this device for over a year. I want to erase all to dispose of it but when I start the procedure as directed to reset, it wants to connect to my iCloud and I'm afraid it will alter iCloud files. I don't want to upload or save anything on this device and I don't want to affect my iCloud that exists for all of my other devices. When I start reset it wants to connect as "App Data Not Backed Up". It says data from iTunes U and 72 other apps will be permanently deleted. That is fine, those items were backed up when I got the new iPad. My fear is if I back up now it will displace or alter other data in my iCloud accounts. Again, I just want to let this one die so I can safely dispose of a broken unit.