What flush cut off tool to use?

[# Fred #]

Friend is removing his flooring but the underlayment he wanted to remove go under the walls. So far all he could do is going around the rooms with a circular saw leaving about 2" underlayment sticking out from all the walls. Is there a tool that could cut the 1/4" plywood underlayment flush to the walls all around the house without burning itself up?

[Charles Sedivy]

A jamb saw would work- looks like a router with a circular saw blade mounted at the bottom. Home Depot tool rental has them, not sure where else.

[Craven Morehead]

[# Fred #]

Is there a wood cutting blade for a 4-1/2" angle grinder?

My manual jamb saw will take forever.

[Craven Morehead]