McDermott's last appearance was in the 1-0 home win over Barnet last weekend.
He said: "Everyone at Chesterfield was really welcoming during my time there. Chesterfield is a good club to come to.
"The reception I got at the end of the game really meant a lot to me. I didn't know what to expect and then at the end I saw the fans lined up around the pitch wanting to shake my hand so I thought I'd go round.
"I'm pleased we got the three points in my last game because Chesterfield really is a great club."
Meanwhile, Colchester midfielder David Perkins has extended his loan deal with Chesterfield for a further two months and is available to play in the FA Cup.