On PICs with the option of using /MCLR for an input, you enable or disable the reset function using the config word.

If you're using the default PM assembler you can add config options to your code to over ride defaults in the device header file.

@ device mclr_off, xt_osc, wdt_on, pwrt_on, lvp_off, protect_off

Or you can just disable /MCLR with you programmer software before programming the part.