To say the least, I'm a little bit confused.
Normally waterblocks are installed on new systems in lieu of a standard metallic heatsink/fan assembly. They are not removed unless something is being upgraded or transported to a new case.
Whatever cooling apparatus is used, they are all attached in more or less the same fashion. A thin layer of thermal paste is applied to the surface of the processor package to provide a nice thermal barrier between the uneven metal surfaces. The cooling apparatus is then secured in place using a combination of metal brackets, screws, springs, and standoffs to keep it from moving.
Disassembly is performed simply by reversing the steps. Remove any nuts that may be securing the cooling apparatus, then remove any front plate which may be holding the cooler in place, and then finally separate the cooler from the CPU.
Some thermal pastes cure over time which can cause them to act like a mild adhesive. The cooling apparatus may appear to be stuck to the CPU, just give it a light tug while the CPU itself is still secured and if all the restraints have been properly removed, it should come free with little resistance.
As for "delidding a CPU" I assume you mean removing the cap on the processor package so that the cooling apparatus can come into direct contact with the heat generating surface. If that is indeed the case, don't ever do that.