When driving the shaft out it would be advisable to use a press but most boaters don't have one so I am showing you an alternative method. If you are of a mechanical mind set and own a lead or brass hammer then it would be OK to tap directly on the shaft as brass and lead are softer than the shaft material. If you do not own a soft metal hammer simply insert a block of wood such as Maple, Oak or Teak, as I have done here, and tap on the wood with a regular hammer.
Please remember this is a light tapping not a smashing or pounding.
If the shaft won't come out, with some gentle taps, add some PB Blaster, let is soak over night, and try again. If you still don't have any luck drop it at a machine shop and for about $5.00 or $10.00 they will press it out for you. I have never seen one that required this but with boats anything is possible..