The Modesto Bee says 22-year-old Denise Helms of Turlock posted the inflammatory comments on the social media site shortly after the president's re-election on Tuesday.
She used the n-word in referring to Obama and wrote that maybe he will be assassinated this term.
Helms then told a Sacramento TV station that she wouldn't mind a bit if someone assassinated Obama.
Helms was fired Thursday from her job at the Stone Cold Creamy store.
Store director Chris Kegle says the comments are disgusting.
Secret Service Agent Scott Gillingham in Sacramento says the incident is being investigated.
Threats against the president can lead to felony charges.
Information from: The Modesto Bee, http://www.modbee.com