Spool removal is pretty simple. Some reels have either a plunger style system or a thumbscrew system for locking on the palming side plate. Both are located in the same place on the reel. If you have a right handed retrieve reel, towards the front on the right side, you will see either the plunger or thumbscrew. It is actually the bar that goes from one side of the reel to the other. With the thumbscrew version, simply back off the screw counterclockwise. The screw is spring loaded, so once loosened the screw will pop out and stay in place. Next, grasp the palming side plate and rotate UP towards you. The side plate will rotate up about 30 degrees. Simply pull the palming side plate directly off the reel. From there you can pull the spool out of the reel. WHEN THE SPOOL IS OUT OF THE REEL, AVOID TURNING THE HANDLE. The brass pinion gear is not lined up with the drive gear, so turning the handle would cause the two to turn out of balance, therefore damaging the gear teeth.
Installation is reverse procedure as above. Keep in mind to place the palming side plate at that 30 degree angle and rotate the cover DOWN. If for some reason it seems tight to rotate down, you probably have too much tension on the spool. On the right side of the reel, back off the cast control knob and the tension on the spool is decreased. This should solve any issues with reassembling the palm side plate. When tightening the thumbscrew, I suggest finger tight first, then with a small flat tip screw driver, tighten no more than a ¼ turn more.