Hello there @Kuroshi,
I believe they have this article called Function reference which includes all the function that you can use in a formula. Here it is: https://howto.caspio.com/function-reference/. You can check the replace function as this can achieve your current workflow. Here's the formula:
replace(replace(replace(replace(replace([@field:Name],'a',''),'e',''),'i',''),'o',''),'u','')
You can change the field Name, by the way.
Hope this works.
- Barbie