If the bike is USED it is possible (unlikely, but possible) that the previous owner has had issues with the adjustable cup coming loose and has assembled it with a couple of drops of blue (removable strength) Locktite.
If this is the case, you are going to need some heat to soften it. Not too much heat... In rare instances where hand tools do not work because of excessive engagement length, apply localized heat to approximately 482°F (250°C). Disassemble while hot.