Hi there,
Merch uses a bunch of Elements – ( the Hook, Header and Layout element ) to create the Custom Post Header:
https://docs.generatepress.com/article/elements-overview/
All of them are accessible from Dashboard > Appearance > Elements. And are titles as so:
1. Single Post Header Featured Image
This displays the large featured image if one is set.
2. Remove single post title
This removes the default H1 post title.
3. Single Post Entry Header
This adde the post meta and large title above the large featured image.
4. Fade Out Post Nav
This loads the Javascript to create the fade in effect.
You can either permanently delete them or Quick Edit and change their Status to draft to disable them. Probably best to draft them so you can see what is what before deciding to delete them.