Edit vold.fstp to swap internal to external sdcard

I am using HTC desire 516 dual sim phone and unable to do anything with 145MB space left in internal memory.
I have rooted my phone as it was already out of warranty and have RootExplorer to access vold.fstb file.
However unable to do so as my file says only
(dev_mount sdcard /storage/sdcard1 auto /devices/msm_sdcc.2/mmc_host) and I am unable to identify the change.

Please help.

Ritesh