How to remove an older Shimano Hollowtech crank?
Every Shimano crank has its model number stamped on the inside of the arms.

If you have an Octalink BB, all you need is either an Octalink crank puller or an adapter.

Below is an adapter type tool. It fits in to to the end of the spindle so that any normal square taper type crank puller can be used. They work as well as anything and only cost a few dollars, or at least did when they were a more commonly seen item, so if you have a crank puller already they're a good choice. There are some different ones out there that are all basically the same thing, and I believe they can all do both Octalink and ISIS. (I have a non-Shimano one that can and I think the Shimano one pictured can too, but not 100% certain.)



Some crank pullers can do both Octalink/ISIS and normal square taper, like Park's one with interchangeable bits:



There are also Octalink/ISIS-only crank pullers. They're kind of the least desirable option if you're buying tools these days because these cranks are relatively uncommon, despite the years from about 2000-2004 where there was the perception they were going to be the new normal.