can I cancel my neet 2019 MP online counselling registration, and then register again

There is no correction window and so you cannot edit the category details. But registering again will cost you money. And it is not certain whether multiple applications are allowed. First please write to them at mpugpg2019@gmail.com and if they say it is not possible then you can register freshly again. You can also call them at 07556720204. Please refer to the website https://dme.mponline.gov.in/portal/services/dmemp/DMEUG/Profile/ProfileLoginHome.aspx