1
general::
Get rid of by selling, often at reduced prices. For example, The jeweler was eager to sell off the last of the diamond rings. [c. 1700] Also see SELL OUT, def. 1.
American Heritage Idioms
2
general::
Phrase(s): sell something off
to sell all of something. • We ended up with a large stock of out-of-style coats and we had to sell them all off at a loss. • We sold off all the excess stock.
McGrawhill's American Idioms And Phrasal Verbs