A lot of companies have title blocks designed so that the border on some sides is set to <Invisible lines>. This has the limitation in that you can only see the border if you hover your cursor over it to highlight.
And since Revit does not have a non-printable line, you simply cannot draw any other kind of line.
- One way around this is to use a Guide Grid.
Create a new Guide Grid and name it the same as the sheet size, i.e. Sheet A0.
- Make the extents of the Guide Grid the same as the area you want to define.
- Change the Guide Grid’s Guide Spacing to something larger than that sheet size.
This will give you just a single blue border which is not printable.
Create a Guide Grid for every size sheet you would typically use in projects.