Yes , you also can apply online for PRMO, here HBCSE will release online application window most probably in the first week of June (depends upon the conditions also) on mtaexma.com, as you didn't mention your anything so that we could check your eligibility for this so still you can see basic eligibility criteria which are mentioned here:
Candidate must be from class 8th to 12 .
Your age must be after 1 August 2001.
Only Indian citizen and students who are having OCI certificates can apply for PRMO 2020.
for more criterias and details you can refer given link:
Best of luck.