No need to remove the drive. As I explained in your other thread it can be done relatively easily. Remove the end cap of the drive behind the propeller and anode and that contains the seals. It also exposes the shaft so you can check for wear. Doing this automatically results in the oil draining, but it is till worth removing the drain plug at the bottom both to drain the small amount of oil that lies under the shaft, but also because it is difficult to remove if it has been in a long time. You can then replace it so it is perhaps easier to remove if you want to drain the oil in the future.
Google Volvo saildrive oil seal replacement for lots of information and videos. If the shaft is worn then google volvo saildrive shaft sleeves and you will find information on using SKF Speedi sleeves to repair the shaft. Replacing the seals is for some a DIY job, but sleeving the shaft is a workshop job. Volvo and aftermarket suppliers like Keypart in the UK sell seal kits to do the job. I expect there are aftermarket suppliers in the US and Canada as well.
If there is water in the oil then early investigation and repair is advised!
