Hey all, just some useful information for people in the future in case it's required. I'd emailed Chris at EFI Parts for some advice around removal of the kpro ECU, this is what he kindly came back with.
I think you're going to need to swap the whole ECU for an original type and have its immobiliser coded by Honda. I may be wrong, but I'm fairly sure that the ECU you have now will no longer run if the K pro is simply removed.
The ECU is physically modified to accept the Hondata board and the software loaded on to the ECU is custom also. Someone, somewhere may be able to flash a stock file back to the ECU in order for it to run without the K pro module present.
You'd do better to swap the whole ECU since you'll be able to sell your Kpro ECU in its entirety then.
Beware though, your DC5 will likely have a PRB or PRC ECU. You'll need to replace it for the same type. UK EP3's use a PRA, which is not compatible with your cars lambda sensor and possibly some other aspects.