removing excess cured silicon

[bycatch]

Hi all,
The tank I'm setting up has some (in places way too much) excess silicon.
This is well and truley cured. I have had the tank full of water for 14 days to see if it leaks. This is when i noticed the excess.

The guy who built it used braces in the corners as he used 6mm Optiwhite and needed the strength.

Can I remove the excess by using a blade and carefully, without cutting into the joint 'scape' off the excess?

I imagine I'll have to run another bead around where i've been - and clean off excess before it cures?

Mike