The 28-year-old Bulgarian was working with Radek Stepanek, but said the two had split, though he is still using Andre Agassi as a coaching consultant.
He added that he was looking for a coach but is in no hurry to find someone. "You should not allow anyone to control your thoughts and your game. The moment someone tries to cage you, that is the worst thing that can happen to a competitor," he said.
But Dimitrov indicated there is still regular contact with Agassi, though the eight-time Grand Slam champion does not like to travel as a coach.
"Agassi is still with me," he said. "In the important moments, you can count on him. Our relationship goes beyond tennis."
Dimitrov, who won the 2017 ATP Finals and has been as high as No. 3, was No. 78 coming into the US Open. But he reached the semifinals at Flushing Meadows, and then again got to the semifinals of the Paris Masters, allowing him to finish the season at No. 20 in the rankings.
During the season, he had spoken about his problems with an ongoing shoulder injury, which left him sidelined and frustrated but more determined to resume his career.
"When I was No. 78, I didn't think I could finish the season this way. Two tournaments created a turnaround," he said.
Starting the offseason with a vacation in Iceland, the Bulgarian now plans to get back to training and keep his comeback going.