The duo have told how they were close to walking away from the show in 2012 after a clash with show boss Simon Cowell.
The pair share the details in their upcoming book Once Upon A Tyne which celebrates 30 years working together.
In an extract published in The Sun newspaper, Ant and Dec speak about how they felt "sidelined" after most of their work was edited out.
Ant writes that the duo felt as though they were "wasting our time" on the show and considering quitting.
It led to a tense meeting between Ant and Dec and Simon where the TV hosts say they "let him have it with both barrels".
Ultimately Simon vowed to make amends and Ant and Dec have continued to front the talent show ever since.
The new autobiography from Anthony McPartlin and Declan Donnelly is available to pre-order online now by clicking here.
Celebrating 30 years together, Ant & Dec look back on three decades in the spotlight, with the full behind-the-scenes story and never-before-seen photos of the shows that made them the nation's best loved stars.
Released on September 3, the book is available in hard cover, audiobook and Kindle editions.
As well as hosting Britain's Got Talent, the pair also currently front I'm A Celebrity and Saturday Night Takeaway.
They first began their careers in 1988, appearing as child actors in children's television show Byker Grove. They went on to become known for their TV hosting work on shows such as SMTV Live and Pop Idol.