Most likely they are suckers growing from the roots. Most Lilacs are grafted so these would not be worth keeping in any case. You need to trace back to the root and cut out the shoot with a little bit of the root otherwise any buds on the shoot would regrow. This procedure does little harm to the shrub as the root will soon heal over. Time consuming though as I know too well.

ditto

but that is really the only way to tackle it.

ty there is loads of them so im going to be busy hope the weathers nice

Sorry, but there it is. Been there done that so I know what it is like.

My mother used to to this every year...