Leaking toilet?

If a close coupled cistern / pan unit ie cistern sits on pan you will have to remove the cistern if it comes to it.
If low or high level system then it's a matter of removing the flush tube from the rear of the pan then the screws in the base of the pan, if fitted.

With a pan fitted into cast iron collar first try sealing off leak with mastic, failing that you may find the joint in such a bad state you can ease the pan out with very gentle side movemnet to break the seal. Clean up spiggot and C.I collar. Sometimes you have to break the pan around the spiggot [the bit that fits the pipe] which of course means new pan.

bob
August 2009