You must first set up an outpost and build a ship docking station to do this.
The kiosk will simply invite you to sell your ship.
In general, you will want to sell any unwanted inventory of any stolen ship for additional credits.

Be sure to visit a trading kiosk or merchant to sell these items before you sell your ship.
Because the ship is stolen, you must firstregisterit to sell it.
This costs a fee equivalent to around 90% of the full price of the ship.

Once you pay the fee, you will then be able to sell it as normal.
That’s everything you oughta know to sellStarfieldships.