But depending on the current flavour and concentration which you wana bring it down to, you can consider this..
0mg HC E-juice/E-Liquid(PG Base. 46 flavors)
Let's say u are currently holding to a 24mg/ml menthol flavoured liquid and wana cut it down to 1/2, just get non-nic flavoured liquid and dilute it using a 1:1 ratio..