Trouble removing tank

[NOTHING ELSE MATTERS]

Guys, i'm restoring another boat now and i have a very big problem, i can't remove the gas tank. This thing is like is glued to the bottom of the boat. I removed all the foam except from the bottom and also the port side stringer, this thing doesn't budge. So my question is, can i cut it in pieces with a grinder?
The tank has been empty for the last 3 months and i can't smell any fumes when i stick my nose in the sender hole(sender and all hoses have been removed).