in thevenins theorem when thevenins voltage source is short circucet the resistance across the thevenins voltage will removed what is the reason to remove the voltage
For an ideal voltage source the internal impedance should be zero. So we 'replace' Thevenin's voltage sources with short circuits or try to make the Thevenin voltage as zero for making an ideal voltage situation for 0 internal impedance hence it becomes or this condition is known as short circuit.