Many of us have no problems with Evri deliveries and any seller who cancels just because of the courier they selected is likely to receive negative feedback. I'm sure the same is also true for DHL.

And what reason are you going to give when cancelling? I hope you are going to take responsibilty for the cancellation and not going to claim buyer requested the cancellation or problem with buyer's address. My advice for inexperienced sellers is that this is probably a very quick way to lose your selling account!