how to remove overflow and bulkheads?

[c_scherer123]

Not sure if this goes here...

I have a 90g drilled tank, I wish to turn it into freshwater and get rid of the sump. It has a built in corner overflow and the bulkheads were firmly siliconed in. What is the best way to remove them? Any tricks or tips?

I considered exchanging it for non-drilled, but it is too heavy to carry up the steps; it must weigh at least 250-300lbs...