Start loosing the two horizontal bolts that holds the lower rudder fiting together. It is made in two parts in order to avoid having to take the rudder down. You have to move the rudder from side to side in order to access the bolts.
If you have a wheel steering or other parts such as autopilot drive attached to the rudder shaft, this is best removed first, to allow more movement from side to side.
The second part is fitted to the skeg with 3 vertical bolts.
The 3 bolts hold the bearing to the skeg. These 3 screws need to be loosen. Then give the fitting a good slam with a hammer, as it is enbedded in putty (Plastic Padding).
When re-installing the bearing again to the skeg, some precission is required, to make sure alignment is OK. This is done with the putty you apply between the part that again is bolted to the skeg with the 3 bolts.