How to cut or remove the unwanted waveform?
The probable cause is that you have a relatively slowly rising signal edge (magnetic field change) that has noise on it (electrical or mechanical) so that it crosses the trigger level several times as it rises or falls. The sensor orientation may matter. Changing its angle relative to the magnet that it is detecting, or rotating it 120 degrees along its magnetic axis may help. Or not. 

The Chinese sensor SHOULD be "good enough". Check power supply filtering to it. Is that a polled sensor or always on? Please provide a datasheet link.

What voltage is the Hall switch working on? Presumably the signal range and power supply voltage are about the same.