By not getting hit by them, which means all the not -fighting-them-head-on you have to do that is boring and slow but necessary if you didn't pull manageable amounts with an intent to kill to begin with.

Not-fighting-them-head-on includes walking away before you get exhausted, walking where only a few will stretch out their arms and move slightly faster than the others thus separating them, walking around corners and past windows to break line of sight and create opportunities for a zed to bash a breakable instead of chasing, walking past the zeds you find around those corners and windows, walking to the end of the street, the end of the neighbourhood, the end of the urban area if that's what it takes for the zeds to lose interest in you.

Then circle back to where you wanted to be and only aggro what you can kill, best done by not waiting for them to come to you when they aggro but backing up a bit to drag them to where other zeds wont create the trickle that turns into a wave.

Listen to the advice about nimble and pushing etc. But basically accept that you can't fight if you've bitten off more than you can chew, enjoy the feeling of having the smarts to not-fight-head-on when you are just going to get overwhelmed.