Bypasing LDO voltage regulator
Usually nothing happens so yes, you can just do that (short input and output).
What happens is that the internal feedback of the LDO notices that the output voltage is higher than what is should be (for example 5 V instead of 3.3 V) and that will cut off the regulation transistor. Which is OK because the current will come through the short that you added.
To be sure, include the datasheet of the regulator that you're using so that we can have a look and confirm that it will work as I explained above.