Hi and welcome to the forums.
The recommendation will always be to try to get the EXUP valve working rather than ditching it as it is an integral design to the bikes performance characteristics. If you are getting the 7K tachometer code this could be as simple as the cables needing adjustment, or the valve may be seized. The guide Panthor posted would be your first port of call to strip the valve assembly down and check what the issue may be.
To answer your question you can remove the valve and blank the hole off and this will resolve the 7K code, but you will be left with a weaker low end and a flat spot around 5K.
The recommendation will always be to try to get the EXUP valve working rather than ditching it as it is an integral design to the bikes performance characteristics. If you are getting the 7K tachometer code this could be as simple as the cables needing adjustment, or the valve may be seized. The guide Panthor posted would be your first port of call to strip the valve assembly down and check what the issue may be.
To answer your question you can remove the valve and blank the hole off and this will resolve the 7K code, but you will be left with a weaker low end and a flat spot around 5K.