Share 'USHER SAYS HE 'RETIRED' NOT 'FIRED' HIS MAMA: Singer says he let her go last year to be a full-time grandma.'

*Usher wants to make it clear that he did not fire his mother as his manager just days before Mother's Day last year. He simply "retired her," the singer says in Vibe magazine's July issue. He admits to having disagreements with his mom, Jonetta Patton, over what he felt was her lack of support. (Their fall out led to her skipping his wedding to Tameka Foster last August.) But he says the sepa…