Most Lucas (and other brand) molded connectors that take spade lug terminals can be disassembled.
Start by "drawing" or photographing the connector so you know which wire goes back where. Find a relatively short bit of small diameter steel wire like a paperclip. Straighten out a bit of the wire so it is about an inch long. Look into the connector entrance at the terminals. You should see a little square or rectangular openings along the long side of each of the terminals. Insert your wire into that small rectangular opening and push the steel wire towards the brass terminal while tugging in short pulls on the electrical wire. Eventually you will get to the point where the steel wire has pushed the terminal's locking tab back into the terminal and your tugging on the wire will allow it to be withdrawn to the rear.
When you go to push the terminal back into the connector you may need to pry the little locking finger back out of the wire end terminal so it will catch again in the plastic connector.
The image below shows a side view of what I was trying to describe above.
All that said... cutting the grommet as Jim said and using Krazy-Glue to re-connect the cut ends is easier than taking the connector apart and putting it back together.