Angle grinder with a cut off wheel. You will be there for a week with a dremel.
Cut along the welds about an 1/8" away from the sheet metal. Take your time, Don't put the cut off wheel in a bind, they will shatter.
'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...