Boothroyd has already told centre-half Anthony Charles that his contract will not be extended beyond the end of this season and hopes that the 31-year-old will find another club this month.
With Clarke Carlisle recently signing an 18-month deal and John Johnson and David Artell on the verge of returning from long-term injuries, the Town boss believes he has enough options at the back.
"We are a little bit short in some areas, but the squad is 'bottom heavy' because we have got too many defenders," Boothroyd told the Herald & Post.
"There has got to be a bit of leeway and a bit of shifting.
"Ive spoken to Anthony Charles and I've said that he won't be offered a new contract. We hope that he has got an opportunity to leave which will open a spot for someone else.
"That's how I like to work - if I know I'm not going to take somebody then I'll tell them. We can move him on and bring one or two in."