Computations are performed with limited resources. So if you want to handle more complicated input, please download and compile the programs on your own.
You can input a deleting rewrite system here, and I will show its transformation into a product of a substitution and an inverse context-free system.Note that the system has to be deleting w.r.t. the alphabetical ordering (a > b > c > ...), and left hand sides of rules have to have distinct letters.
For comparison, you can use change bounds as defined by Ravikumar. Note that this only work for length-preserving systems.