In my experience ( i am sure there are others with more knowledge and more experience than I) but i remove the caliper and then slide the pads out. Nissin and Brembo have different retaining clips, and are a little different in the assembly, but it will make the job a lot easier, and only takes a few more seconds to undo the caliper..
(i did this often, every few weeks with my 08 D675... and still do it frequently with my 13 D675R)
The reason... I like to inspect the function of the caliper. Visually inspect each piston as i clean, and check the pads.
If you are wanting to get the pads out to replace, or just check, why not give the caliper a good clean. Brake cleaner or some good ole soap and water. even flushing the brake fluid, at some point i will remove the caliper before/ after to clean/ assess.
I looked back through and couldnt find the HOW To either... i know i saw one last year.
If you are still having trouble, i will post one up tomorrow... given... it will be on the R model with brembo, but follows the same principals.
Let me know if you need more help
( this is a good video to follow to make sure you have the right tools/ equipment/ knowledge. it is another bike... but the rules stay the same)