https://www.homedepot.com/p/Roof-Zone-Serrated-Roofers-Spade-with-wide-heel-Steel-Handle-13874/301759220 This thing.
Its worth your back bending over on a roof cutting up small pieces with a worm drive but if you must,
https://www.bigrocksupply.com/store/p/6212-Roofers-Carbide-Circular-Saw-Blade-7-1/4-in-14-Teeth.aspx
That pitch fork thingy will remove a lot of the nails. Start from bottom up. My roofer will have 5-6 guys strip a roof with those simple tools in half a day while the dump truck is parked on the driveway as they pitch the roof into it.