Hungerford received an official seven-day approach from league rivals Wealdstone for Ngamvoulou and he wanted to make the move closer to home.
The Crusaders agreed to waive the approach, allowing him to make his move sooner.
Ngamvoulou joined Hungerford in July.
He signed for Margate from then-National League South rivals Oxford City before last season`s March signing deadline.
Ngamvoulou has plenty of non-League experience after starting his career in England at Staines Town following a spell in his home country with SO Romorantin.
After a period at Farnborough, the 28-year-old joined Whitehawk where he showed real promise in the attacking midfield role.
Loan spells at Hednesford Town and Boston United followed before he signed for Oxford City in December 2016.
Ngamvolou said: "It is with a heavy heart that I wasn't part of the game on Saturday as I am leaving the club.
"Both the club and I had to see in the long-term so I understand the decision. Playing at Wealdstone will be the first time in four years that I have been close to home and will allow me to concentrate on my work more.
“I would like to thank the players the supporters and everyone around the club who made me feel so welcome. I wish you nothing other than the best for the future, it is never easy to find a place in the changing room for a foreigner but you all made it possible and easy for me, merci beaucoup".
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