Theoretically, you can, but you have to pay the registration fee, examination fee, appraisal fee and certificate fee. But the specific situation varies from place to place. Some places entrust the registration work to training institutions, and the training institutions require you to participate in the training. So I hope you'd better call for advice. If it is the China IOT exam, call the designated local exam center to ask. If it is a national labor department exam, call the local vocational appraisal center to ask.