Yes you can deep fry frozen potatoes.
There's no need to thaw the frozen potatoes or frozen french fries out before deep frying them.
Just make sure you put the frozen french fries or frozen potatoes into the deep fryer oil before you actually get the deep fryer oil hot.
If you add the frozen french fries or frozen potatoes into the deep fryer when the oil is hot it could create a flash back of the oil and cause burns as well as a potential fire.
But if you do add the potatoes that are frozen to the hot cooking oil put the frozen potatoes or frozen french fries into the deep fryer basket first and then slowly lower the basket into the deep fryer.
I cook frozen potatoes or frozen french fries all the time and never thaw them out first.