I installed a new tile floor. The toilet flange is to high and the toilet sits about a 1/2 inch off the floor. What can I do to install the toilet?

Since you didn't say I'm going to assume that the pipes are PVC. Cut the pipe and flange off at floor level and install a inside closet flange,(see image).
You may have to secure the inside flange to the floor. See instructions. Good luck, Tom

I am sorry I did not state that the pipe is cast iron. I installed a new tile floor. The toilet flange is to high and the toilet sits about a 1/2 inch off the floor. What can I do to install the toilet? Thank you for your previous reply.

Same answer, different method. Break the old flange out and remove the lead joint. Now take a crescent wrench and use it to "nibble" off the cast iron pipe down to floor level. Take small bites. You may now install a cast iron inside flange,(see image). Good luck, Tom