How do I detach a bench seat from floor brackets?

[MJRemi]

I want to transfer my A- condition grey cloth bench seat onto the bracket/slider assembly of my B- condition burgundy vinyl bench seat. It appears the entire seat frame is riveted onto the assembly. The P.O. of the grey seat welded the slider to the rear-most position which is too far for me and limits access behind the seat. Does anyone know how to detach the seat from the frame or sliders?

[dragonsfyr]

We used a sawzall to remove the brackets so we could mount them on my bucket seats.

[ParadiseMJ]

Yes indeed, they are riveted together. I used an angle grinder and a drill