The Rhinos ran in 11 tries at Belle Vue on Sunday to book their place in the fifth round of the competition.
Despite his team starting the game nervously, McDermott is pleased that they were able to steady themselves and get the victory.
"I thought it was a tough opening first quarter. We bombed a few chances and while it appeared we looked dominant, I've been in enough of those games to know they just needed one thing to go their way," he is quoted as saying by Sky Sports News.
"I think the players were feeling [anxious] up until about that 15-minute mark, but after that we were very dominant, very switched on and equally I thought our mentality towards today was where it needed to be."
Leeds face Wakefield again on Friday when they welcome them to Headingley Carnegie in the Super League.