Hey Cokisa, If you recently registered for the Umoya Manje service and now wishes to deregister, then simply dial the same USSD code you both used for reg and taking the airtime credit and select the "Deregister" option. If you however have somebody who is using you particulars to benefit from the Umoya Mamje service, then there is sadly no direct way to stop this from your phone either than phoning the company in charge. Refer method 2 here http://www.satechhelp.co.za/482/Stop-Umoya-Manje