The private drop boxes were found in Los Angeles, Orange and Fresno counties, stirring up complaints about possible election fraud.
Republicans say the private boxes comply with voting regulations.
The state says someone must be posted with the boxes and that people transporting ballots must sign for them to take custody of the votes.
RELATED: California Republican Party placed illegal ballot drop boxes in LA, Orange and Fresno counties
Last week, state Republican Party leaders said they would not comply with an order from the state's chief elections official to remove the drop boxes.
Secretary of State Alex Padilla and Attorney General Xavier Becerra, both Democrats, said the drop boxes are illegal and ordered Republicans to remove them. They worry voters will confuse the Republican boxes with the official ballot drop boxes put in place and monitored by county election officials.
To find early voting and vote-by-mail ballot drop off locations, visit https://caearlyvoting.sos.ca.gov/ and to make sure your vote is counted, visit https://wheresmyballot.sos.ca.gov/.
The Associated Press contributed to this report.