Remove the string valNameString as a string value of the concept aConcept's attribute that has name attrNameStr.
NULL = rmattrval(aConcept, attrNameStr, valNameStr)
aConcept - type: con
attrNameString - type: str
valNameString - type: str
Nothing
rmattrval also removes the attribute.
G("Malibu") = makeconcept(findroot(), "Malibu");
addstrval(G("Malibu"),"Latitude Direction","North");
rmattrval(G("Malibu"),"Latitude Direction","North");