Old iPad Air

I have the original iPad Air. I don't really use it anymore, but I did just update it to the latest ios and I do like having it functional.

Here is my question...my husband would like to use the ipad for a Rotary fundraising event. There will be multiple people using the ipad. Is there a way I can lock out all my stuff - photos, messages, files, but allow the Rotary club to use Square for payments?

Also, I have created an Apple ID for them. I thought I could sign out of my ID and sign in to theirs, but when I go into Settings, my name and Apple ID is grayed out so I can't access it. Possibly this iPad is too old for such endeavors?