you must remove the roots.

Dig them out?

Aside from the seed heads the tops will make good compost!

if you are not in a hurry to get the garden sorted out cover them with black polythene after youve chopped the worst down.you can also get some salt from somewear that sells central heating or a plumbing place and spread that heavily to . if your in a hurry then the advice above is right .

the new shoots you can eat as it goes thow ive never tried.

You wont be able to grow anything for a while if you put salt in concentration on the soil.

no like i said if your not in a hurry to regrow even with just the polythene you would have to weight a seasen realy .

Best not to pollute the soil if possible. As you wil kill all the wee beasties in it too - and not just the ones you don't want!

it worked for me but you could just use the blackpolythene if you wernt in a hurry.