there's a variety of ways to deal with this.
1 - download one of the park it mods & take it out of the tab list
2 - open the vehicles.xml in the gamesave folder & change the property state from "1" to "0". The vehicle will still be in the game, you'll still be able to get on it & use it, but it won't appear in your tab list or your "garage" on the purchase menu
3 - you can also just delete it entirely if you have Easy Dev controls.
Open easy dev, enable delete objects, walk up to it until it appears the option to delete appears on your screen & choose it