Even if you release the brake lever, it will be in locked position and this causes the bike to skid, dangerously!. ABS detects this kind of sudden lock and applies pressure to release the lock ...
It should turn off after you cross 5km/hr speed. If it does not turn off then there is an issue with the ABS system. You have to get it fixed by authorised RE service center ...
which was the only sub-125cc commuter bike to come with single-channel ABS. The Platina has been a long-running model in Bajaj’s lineup and this erstwhile ABS variant was the most expensive.