Alexander Rossi has ended his working relationship with Caterham, saying he is "ready for the next step" in his career.
The American first tested for Caterham back in 2011 and have been part of their Formula Renault 3.5 and in GP2 set-ups over the past few seasons.
He was promoted to reserve driver in 2013 and has had several Friday practice outings while his next FP1 assignment was due to be at the United States Grand Prix.
However, the 22-year-old has confirmed he has parted company with the Leafield squad and won't race for them in GP2 in Germany this weekend.
"I'm very thankful to everyone at Caterham throughout the time I have worked with the team," he said. "We had meetings over the past couple months with the previous and new management.
"The decision we took to leave Caterham is the right decision for my career.
"I take with me only the positives from my time there, where I logged considerable F1 mileage, driving each of their F1 cars since Lotus Racing entered the F1 World Championship in 2010. I have proven my abilities in F1 equipment, in both testing and free practice sessions, and I'm ready for the next step."
Caterham was recently sold by Tony Fernandes to a Swiss and Middle East consortium with Christijan Albers placed in charge of the day-to-day operations of the team.
The team have already held talks with Carlos Sainz Jr about a possible race seat while they have also launched a Development Driver Programme.
Rossi, though, is determined to remain in Formula 1 and has set his sights on a race seat.
"My goal is to be in F1 and add value to the sport," he added.
"We have a great opportunity to grow the sport in the States and I believe the timing is perfect. I'm also very pleased to see an American F1 entry, Haas Formula with plans to join the F1 grid in 2016."