Looking at the template, this looks like an issue of certain elements - such as some blocks' inner backgrounds having a particular coloring - being hard-coded in some of the pre-built templates you would find on the template selection page. This can also occur with those kinds of pre-built templates that have unique designs as part of their inner backgrounds, unique pattering, etc.
The only way to go about resolving the issue would be make a new template, or to copy from a different one that doesn't have these un-editable elements in them.
You can also just recreate those particular blocks within the same email, using one of the available layouts, and copy-paste text over. Then you can simply delete the problematic blocks.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ William A Community & Social Media Support