They make a tool for it actually. I don't have one. Instead of busting up my fingers doing it I use a big like 1 1/4" box wrench. I slip the box end over the shifter and use the wrench handle for some extra leverage. I've also done it with two pairs of channellocks, one in each hand. The channellocks make it easier to twist out it seams.
I use one pair of channel locks. squeeze with one hand and push/turn with the other.
In life many men take the path of righteousness, some take the path many others follow (G.M. owners, for example), some take a more arduous path, some a simpler path. I, sir, took the PSYCO-PATH!!