Almost all those Spanish pistols dismount the same way as the M1905 Browning/Colt Vest Pocket. Make sure gun is empty, then cock the hammer. Pull the slide back to some undetermined point, and turn the barrel counter clockwise (as seen from the rear). This moves the lugs out of the frame and into the slide, and allows the slide to come forward off the frame.
I know that "undetermined point" sounds odd, and some guns do have a holdback to postion the slide for takedown, but some, like the Colt, you just have to feel for the right point.
Jim