Another important part of the bathroom-remodeling project is the demolition of your existing bathroom. You need to have a plan. There is a process to the demolition phase and it usually does not require a sledgehammer. It requires a plan and patience. Below is planning guide to the demolition process.
Keep in mind the toilet flange will need to sit flush with the sub floor or the finished floor. If the flange is higher or lower than the finished floor, you may need to replace the flange. This, of course, will add to your expenses.
I strongly encourage you to check and double check your work to make sure everything is done correctly. If at any point you are not comfortable, take a step back and hire the proper professional. Always be sure to follow the local and national building codes.