Nicholas announced on his personal Twitter page Monday that he's elected to retire.
Nicholas agreed to a minor-league deal with the White Sox earlier this month, Kegan Lowe of Baseball America reports.
Nicholas was traded to the Padres on Friday in exchange for a player to be named later or cash considerations.
Nicholas cleared waivers and will return to the Rangers as a non-roster invitee, Evan Grant of The Dallas Morning News reports.
Nicholas went 0-for-3 with a strikeout in Wednesday's 12-2 loss to the Astros.
Nicholas went 1-for-3 with a base hit in Thursday's 5-1 loss to the Astros.
Nicholas went 2-for-4 with a home run and three RBI in Saturday's 8-3 win over the Astros.
Nicholas went 1-for-4 with a double and a run scored in Friday's 8-4 loss to the Twins.
Nicholas was recalled from Triple-A Round Rock on Monday, T.R. Sullivan of MLB.com reports.
Nicholas (knee) was activated from the 10-day disabled list on Friday and optioned to Triple-A Round Rock.