Most fountain pen nibs can be safely and easily removed for cleaning or changing your nib width but the process in which to do so can be different for each brand of fountain pen.
It is important to make sure you remove your fountain pen nib correctly as not to damage the nib or pen or void a manufacturers warranty.
These instructions should hopefully help you to do so with a Kaweco pen.
To start with, it would be a cleaner job if you gently clean and flush your pen out first of any residual ink.
For Kaweco Sport Classic, Skyline and plastic models - the nib and feed are friction fitted, so with a grip of above the nib and below the feed with your thumb and fore finger you can gently pull it from the housing unit.
For Kaweco Sport AL, Brass and metal models - the nib and feed can be twisted anti-clockwise to remove, still in it's housing unit as one.
The nib and feed can be further removed from the housing unit for added cleaning, just gently get a grip of the front and back of the nib and feed alone and gently pull. It may take a little wiggle to remove it. However, this step may be easier while the housing unit is still in the pen.
Some nibs may be a little trickier to remove so using a piece of rubber grip or a washing up glove may help for a better grip and to avoid hurting your fingers. Give it a little wiggle as you pull out the nib.
You can find replacement Kaweco nibs here >> Kaweco replacement nibs