You will need to remove the cartridge from the pen. If you are using an ink converter, you can either clean the pen with, or without, the ink converter attached to the pen. First, you will need to unscrew the grip section of the pen from the barrel.

If you are using an ink cartridge, hold the nib upright and remove the ink cartridge. Remember, if the cartridge still contains ink you will need to be careful to keep the cartridge upright, because the cartridge has been punctured and will leak.

If the pen has been sitting for a while and the ink has dried, you may want to soak the nib. The length of time you soak the fountain pen nib will vary based on how bad the ink has dried.

Next you will need to flush the nib and feed with water. There are a few ways to do this. One of the easiest is to use a bulb syringe. Continue to flush the nib until it runs clear.

Dry the pen with a microfiber cloth. Allow the pen and feed section to dry. You can now reassemble the pen and fill it with ink. Your pen is now ready to use!
Make sure you only use warm water. Never use detergents, cleaners, or liquid soap. These items may damage your pen. For dried ink or tougher cleaning, you may try using a pen flush as well. Proper cleaning and care will extend the life of your pen.