Deleting IOS 9.3.5 on iPad 2?
You have been misled. If your iPad is capable of running iOS 10 (you don't specify the model) then you should see the update notification for it.

To check, follow these steps on the iPad:


Open Settings
Tap on General
Tap on Software Update
You will either get a message that it's checking for an update, or you will see a message informing you that you can update to iOS 10.x, or you will see a message stating that your software is up-to-date


Follow the above steps and let me know what you see?

[EDIT]

I've just realised you had referenced iPad 2 in your question title. This generation of iPad does not support any version of iOS above iOS 9.3.5. This is why you're not able to update to iOS 10.