i want to terminate my umobile account

i bought from shoppee;

U biz 38 postpaid
120gb data
Unlimited call
Rm38 permonth

however seller advice to terminate just by transferring to new operator.

can anyone explain more ? just to say maxis or celcom ? then once transferred can just do nothing is ok?

or better to terminate properly ? the centre a bit far from my place. any umobile dealer can terminate ?

sorry, noobie here