How to Reset Flow Using Sandbox?

hello everyone,

when i try to create a new sandbox in create receipt page to reset the flow, the page composer will not open and i receive a message saying that all fields must be filled. However, i cannot fill the entered amount field since it is read only ( i previously mistakenly set it to read only on create receipt page ). what can i do in this case ? how can i reset the flow ? 

Regards,

Ahmad Sahily.