It will just leek a bit,nothing to worry about,first take out the peripheral hoses and leave for last the main one going to your engine which is the one that delivers the fuel.There is an explanation but I can't explain it in English :stupic
It has to do with the vacuum effect,in order for your gas tank to work,air is needed so the pressure inside it can be adjusted and the fuel pump to work,if the hose that delivers air in your gas tank is taken off then it's like sealing the tank and gas can't go out.Sorry for my nubby explanation but it's the best I can give.Hope things are a bit more clear to you now :cheers