In this photo you can see I have already made the cut through the bearing. The location of this cut is critical if your strut uses set screws. Some boats do not use set screws so the cut location is not as critical but on struts with set screws it's far easier to utilize the set screw tappings to aid in breaking free the bearing.
The location of the cut should be opposite either the top or bottom of the set screw tappings so that the bolts are pushing right at the cut to split it inward. the picture denotes the optimum cut location of you have set screws. Without set screws two cuts 180 degrees apart make for easier work.
Making the cut can be done two ways: #1 Cut it by hand with a hack saw #2 Cut it mechanically with a Sawzall.
I DO NOT recommend using a Sawzall if you are not experienced in its use. Only use a reciprocating saw if you have the skill and ability to finesse it for exacting use. If using a hack saw you simply remove the bade and insert it through the bearing then re-assemble the saw around the strut. Some folks say to install the blade upside down but I honestly find it more accurate and easier to be holding the handle in its proper hack saw orientation. I highly recommend Lenox hack saw blades.
When making the cut for a set screw bend you do not need to cut all the way through the bearing but do cut evenly. You do however need to be about 98% of the way through or thinner than a piece of copy paper. Applying more pressure on one end of the bearing than the other will result in an uneven cut. The saw blade needs to have 100% even pressure to make an even cut. You want both ends of the bearing to become paper thin at the exact same time. If you do cut all the way through and score the inner surface of the strut it's not a huge deal, but, if you do this every time you change a cutlass it will get bad over time.
In this photo you can see that I have cut the bearing paper thin and not scored the strut in the process. I used a Sawzall with a very fine tooth metal cutting blade. I have lots of experience with reciprocating saws and feel quite comfortable with them. You'll have to make that decision on your own. If you are in the least bit questioning your skill please use a hack saw with a good quality blade like a Lenox.