Most fountain pen nibs can be safely removed for cleaning or to change nib width, but the process varies between brands. It is important to do this correctly to avoid damaging the nib or pen, or voiding the manufacturer's warranty.
Before removing the nib, it is a good idea to flush and clean the pen of any residual ink first.
Plastic Kaweco Sport Models (Classic, Skyline)
On plastic Kaweco Sport models, the nib and feed are friction-fitted. Grip firmly just above the nib and below the feed between your thumb and forefinger, and gently pull straight out from the housing unit.
Metal Kaweco Sport Models (AL, Brass)
On aluminium and brass Kaweco Sport models, the nib and feed can be removed by twisting anti-clockwise, still in their housing unit as one piece.
Removing the Nib from the Housing Unit
For a deeper clean, the nib and feed can be further removed from the housing unit. Grip the front and back of the nib and feed and gently pull -- a slight wiggle can help. This step may actually be easier while the housing unit is still seated in the pen body.
If the nib is particularly tight, a piece of rubber grip or a washing-up glove will give you better purchase and protect your fingers.
Replacement Kaweco nibs are available here: Kaweco replacement nibs.