To sell up something (or sell something up) is to sell your business or property and move onto something or somewhere else.
Examples of use:
1. The restaurant hasn’t made much money for the past two years so we’re going to sell up and open a book shop.
2. Maria is selling up and moving to Spain.
infinitive – sell up
present simple – sell up and sells up
-ing form – selling up
past simple – sold up
past participle – sold up
See also, move out and move in
Image by That Canadian Grrl