For hide new button follow below step it may helpful for you:
1. To remove the "New" button please go to 'Setup' and find an object for your page layout. Select 'Page Layout' option. 2. Click 'Edit' next to the Page Layout where you want to remove the 'New' button from. 3. Scroll down to Related lists, and click on the wrech icon. 4. Click on the '+' icon and deselect the 'New' checkbox.
I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too. Thanks, Ajay Dubedi
For hide new button follow below step it may helpful for you:
1. To remove the "New" button please go to 'Setup' and find an object for your page layout. Select 'Page Layout' option.
2. Click 'Edit' next to the Page Layout where you want to remove the 'New' button from.
3. Scroll down to Related lists, and click on the wrech icon.
4. Click on the '+' icon and deselect the 'New' checkbox.
I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too.
Thanks,
Ajay Dubedi
You need to remove the Create access on Opportunity for that profile. Removing the create access will automatically hide the New button.