How do you mistakenly have a pending dispute with a CRA?
CRAs have a mandatory period (usually 30 days) to complete their revinvestigation, and another 5 business days to send the Notice of Results.
There should be nothing on the consumer's end that would mistakenly result in a dispute not being concluded by the CRA.
I would call the CRA and advise them of admin error on their part if the dispute has been concluded but is still showing as pending with the CRA.
As for that being a reason for denial of a GW deletion, I dont see the connection.