what i was really worrying about if i use the delete all theme without the default theme is that my phone will go "black out" and i cannot use it anymore.

so you mean i can do the following steps without master resetting my phone or changing to default theme first:

1) with my present theme i will use the delete all theme, then;
2) install again the theme that i was using or any theme i want to install.

is these steps okay?