Do you think I could install Open GAPPs through TWRP using similar steps as the FP Open guide or should I definitely follow the installation as suggested on the Lineage OS wiki I.e. install via recovery?
I also installed open GAPPs through TWRP. 
TWRP = recovery (more info here: #dic:recoverymode )
Hi,
I installed the wrong Open GAPPs package, how can I wipe this and start again? Is it using the advanced wipe in TWRP?
I used the guide on the Open GAPPs wiki for help with this and it worked. Sorry for the rookie inconvenience https://github.com/opengapps/opengapps/wiki/FAQ