How to remove “Archive:” label from archive title

You need to use the filter get_the_archive_title. It works like the_title filter.
More details about the function that embed the filter here

More in this question remove category tag

EDIT :

When it’s a custom post type archive page, you might use another function to print the title : post_type_archive_title()
Then you’ll be able to hook in the title with the filter post_type_archive_title , but there is no prefix for this function.

So in your template replace the call to get_the_archive_title() function with:

post_type_archive_title();