Deed of Release - how?

I am currently in the process of selling my house, and the purchaser has identified some restrictive covenants that they are not happy with.  The house was built in 1983 and the builder lived on the land next door and put in place various covenants that now link next doors home to ours. e.g. We must ask our neighbour if we wish to erect any sort of shed, pegola etc. on our land and our neighbour can also plant trees and shrubs on our land. Speaking to our current neighbour, they couldn't care less and have no interest in being involved in our property. Although we weren't bothered by the covenants when we purchased the property, the purchasers would like the covenants removed - what is the cheapest, quickest and easiest method to do so? Our neighbour is happy to sign something to say he is fine for them to be removed and has no interest in our property and does not want any monetary benefit for the removal of the covenants. 

Emily - have a read of this thread - Restrictive covenants - what are they and more? · HM Land Registry
I'd also recommend seeking legal advice/assistance 
Land registration is complex, designed to protect legal and financial interests in property. There can be significant consequences for any error. Please consider seeking legal representation. Before making an application without legal representation, it is important to consider the benefits of using a conveyancer.