The 19-year-old started working with Maclagan, once a part of Andy Murray's backroom team, prior to the grass court season but has now opted to go in a different direction.
Their partnership started well when Robson reached the fourth round of Wimbledon but results have tailed off since.
Left-hander Robson made round three at the US Open but is currently on a run of three wins in four tournaments on the WTA's Asian swing that her seen her world ranking dip to 46.
She posted on her Facebook page: "Bit of news... Miles and I have decided not to continue our partnership.
"I want to thank Miles for stepping in on quick notice to be my coach this summer.
"I have great respect for him and a person and coach and look forward to continuing our friendship.
"I will take a couple weeks off to refresh my mind and body and will keep my fans updated on my coaching situation."