Hi,
Yes it is possible to deactivate the profile form that appears after the first login page.
You need to follow the below steps:
- If you want to deactivate the profile form that appears after the first login page :
Navigate to Portal Management Model Driven App->Move towards Site Settings from site map->
Search for Authentication/Registration/ProfileRedirectEnabled record And set the value from true to “false” as shown in below screenshot.

2. And if you want to remove the profile page from portals , then you need to do above setup mentioned in step 1 and then you need to navigate to Web Link Sets->Search for Profile Navigation as shown in below screenshot.

Under Links tab->Delete the link or deactivate it as shown in below screenshot.

Clear your Portal Cache and View the results.

Hope this helps.
If you find this solution helpful, please mark it as accepted solution.
Thanks!
Inogic Professional Services
An expert technical extension for your techno-functional business needs
Power Platform/Dynamics 365 CRM
Drop an email at crm@inogic.com
Service: http://www.inogic.com/services/
Power Platform/Dynamics 365 CRM Tips and Tricks: http://www.inogic.com/blog/