Help with REPLACE

I have a string with some characters I need to remove but it removes only first occurence using Replace function. here is the example:

mystring = '#testmodel #242525'.

replace '#' with '' into mystring.

This replaces only first occurence and the result is:

mystring = 'testmodel #242525'.

But I need to remove all '#' occurences in the string. How do I do this?

Thanks.

Mithun.