Remove any authors who aren't on your shelves, than add some more from your shelves to bring the number back to ten.
swisstone's list was:
Terry Pratchett
Gene Wolfe
Alfred Bester
Jane Austen
Arthur C Clarke
Ursula Le Guin
Iain Banks
Christopher Priest
Stephen Baxter
Jon Courtenay Grimwood
I removed Jane Austen and added Neal Stephenson, so my list is:
Terry Pratchett
Gene Wolfe
Alfred Bester
Arthur C Clarke
Ursula Le Guin
Iain Banks
Christopher Priest
Stephen Baxter
Jon Courtenay Grimwood
Neal Stephenson
Terry Pratchett
Gene Wolfe
Alfred Bester
Jane Austen
Arthur C Clarke
Ursula Le Guin
Iain Banks
Christopher Priest
Stephen Baxter
Jon Courtenay Grimwood
I removed Jane Austen and added Neal Stephenson, so my list is:
Terry Pratchett
Gene Wolfe
Alfred Bester
Arthur C Clarke
Ursula Le Guin
Iain Banks
Christopher Priest
Stephen Baxter
Jon Courtenay Grimwood
Neal Stephenson