You can buy a tool for this from a number of sources. The one for the Poulan is Item number 31115 in the link.

Here is a link that might be useful: clutch removal tools

The Poulan part number is 530031112...you can get it from a Poulan source for about 1/3 of the price than listed.

I made my own by grinding a socket, I think it cost about $4. Just make sure you get a large and deep enough socket to fit over the center part of where the clutch is mounted. In my case that was a 19mm socket. I did make the mistake of not getting a deep socket, it still worked but I had to monkey with it.