To say something stopped or changed, the everyday way is a normal negative with anymore at the end: don't / doesn't ... anymore. (You may also see it written as two words, any more — both are correct.)
not ... anymore, the everyday way
She doesn't work here anymore.
I don't live in Senfarren anymore.
He doesn't smoke anymore.
Try it: Amina moved away last year. She ___ live here ___. (doesn't … anymore / doesn't … no longer / isn't … anymore) Answer: doesn't … anymore — The everyday way is doesn't + the verb + anymore at the end: doesn't live here anymore. "No longer" is a different pattern (no doesn't with it), and "isn't live" mixes up the verbs.
no longer, a bit more formal
no longer means the same thing, but is a little more formal. It goes before the main verb, and the verb stays positive (no don't / doesn't).
She no longer works here.
I no longer live in Senfarren.
We no longer need help.
Try it: In a formal letter: "We ___ require this service." (no longer / don't no longer / anymore) Answer: no longer — No longer goes before the verb, and the verb stays positive: We no longer require it. "Don't no longer" puts in two negatives, and "anymore" goes at the end, not here.
Use one negative, not two
Pick one way. no longer already means the negative, so do not also add don't or anymore with it.
She no longer works here. (one way)
She doesn't work here anymore. (the other way)
Not both: "She doesn't no longer work here."
Not "She doesn't no longer work here." — say "She no longer works here. / She doesn't work here anymore.". no longer is already negative, so do not also use doesn't.
Try it: Which one is right? (He no longer plays football. / He doesn't no longer play football. / He doesn't play football no longer.) Answer: He no longer plays football. — No longer is already negative and goes before the verb, with the verb positive: He no longer plays. "He doesn't no longer play" doubles the negative; "He doesn't play football no longer" doubles it and also puts no longer at the end, but no longer goes before the verb.