According to the Daily Star Sunday, the 17-year-old - who has played Ian Beale's eldest daughter since 2004 - was issued with a final warning after attending a London nightclub while underage.
Despite being reprimanded, Suffield allegedly continued to ignore warnings about her continued misbehaviour, which resulted in a string of meetings and ultimately culminated in her dismissal from the role.
A source at the soap told the newspaper: "Melissa has been hauled before bosses on a number of occasions for her behaviour and attitude outside work. In the end they made the decision to let her go.
"The way she's been behaving out of work over the last few months is not acceptable. Melissa is 17 and wants to go out, have fun and do what she likes. But that kind of behaviour doesn't work when you're on a show like EastEnders."
They continued: "She was given a warning a couple of months back after she was photographed going into a London club. So when things didn't improve they had no choice but to write her out of the show."
An EastEnders spokesperson confirmed: "Melissa will be leaving in the summer. She's had a fantastic six years on the show and we wish her the best of luck."
Earlier this month, Devon Anderson - Billie Jackson in the East-End serial - was banned from attending the British Soap Awards after violating strict BBC rules over advertising by posting a photograph of his intended outfit on Twitter.