curl --request DELETE --user "login:password" \
http://myNexus/service/local/repositories/myRep/content/myGrId/myArtId/myVer
Same works for jar files:
curl --request DELETE --user "login:password" \
http://myNexus/service/local/repositories/myRep/content/myGrId/myArtId/myVer/myArtId-myVer.jar
You also need to rebuild artifact metadata by sending DELETE to:
curl --request DELETE --user "login:password" \
http://myNexus/service/local/metadata/repositories/repo-id/content/group-id/artifact-id