The legendary Bulgaria striker, who capped his storied playing career in MLS with the Chicago Fire and D.C. United, took charge of the struggling side in a bid to steer the club toward European qualification, but he has admitted to losing patience with the club's hierarchy, claiming he has not enjoyed the support he expected when taking up the post.
In a letter intended for the local media, the former Barcelona star stated, “I’m fed up, I’m leaving.
“I agreed to start coaching without a contract and I had a great desire to help.
"I had the support of the players and my staff. We endured until it became clear there's no chance of promises being fulfilled.
"It is not my understanding of fair, transparent and professional work. This is no way to achieve high goals if there's no respect between players, coaches and officials on the one hand, and the club owners on the other."
The 31-time Bulgarian champions have struggled with financial problems in recent seasons, and could only manage a third-placed finish last season.
Stoichkov, who won seven trophies with the club during his illustrious playing career, became the club's fourth coach this year, and its ninth since January 2010.