Q: Can changing the strings on my guitar by removing all of them at once damage my guitar?
A: The short answer is that the odds of damaging your guitar are very low. However, removing all the strings at once from certain guitars — depending on the bridge setup —can make restringing more difficult or require making adjustments to the instrument.
Let’s look a bit deeper: You can change strings either by removing all of its strings and replacing the entire set at once, or by removing and replacing each string, one at a time, without damaging your guitar. However, depending on the type of bridge your guitar has, you might prefer to do it one way or another. If you have a floating tremolo bridge such as a Floyd Rose or Ibanez Edge bridge, the bridge retains its height by pulling against the tension of the strings; removing all the strings at once will cause the bridge to collapse into the body, which won’t damage your instrument, but it may make restringing more difficult, especially if there is a route behind the bridge to allow you to pull up on the bridge to raise the string pitch. And, in some cases, the bridge on a guitar is not actually attached — the string tension holds the bridge in place. In this case, if you remove all the strings, the bridge will fall off, and getting back into the proper location may be difficult.
So, the answer to the question of how much the guitar will be impacted by removing all of its strings depends on the guitar.