Lowther was responsible for launching projects including Altitude 360 Black and planning the opening of Sky Bar, which takes place on 18 February.
He joined Altitude last November from running his own consultancy, whose portfolio included the Conkers Discovery Centre, the National Brewery Centre and Stonehenge Rising.
Altitude London's marketing director Peter Kerwood told C&IT that there is no immediate replacement lined up and that Lowther's contract was a short term one.
"He will continue working with us on an ad-hoc basis on a number of projects which he started," he added.
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