Delete default link types in DNG 5.0.1
One answer
In the project properties you can indicated which link types are preferred (but not delete them) for a particular artifact:
http://www-01.ibm.com/support/knowledgecenter/SSYMRC_5.0.1/com.ibm.rational.rrm.help.doc/topics/t_create_artifact_type.html?lang=en
"7. Optional: Select Preferred Link Types. If you select preferred link types, you limit the link types that are available when you create a link."
The default link types are still available but by default the preferred are shown first when creating links.
http://www-01.ibm.com/support/knowledgecenter/SSYMRC_5.0.1/com.ibm.rational.rrm.help.doc/topics/t_create_artifact_type.html?lang=en
"7. Optional: Select Preferred Link Types. If you select preferred link types, you limit the link types that are available when you create a link."
The default link types are still available but by default the preferred are shown first when creating links.