You can do two things:
1) You can go to your project settings under MyEclipse > Validation, and turn off HTML Validation.
2) Or you can go to MyEclipse > Validation > Exclusion (or right-click on the files individually) and mark all the FTL files as excluded from validation.
I prefer #2 since it allows real HTML files to still get validated, BUT if you don’t have any full HTML files in your project, #1 will be much easier/faster.