Input

```
String s1 = "This Payer Ref [customerRef] does not exist/This Card Ref [cardRef] has already been used."

```

I want to remove all the parts with [variable]

Output 

```
"This Payer Ref does not exist/This Card Ref has already been used."

```

Please note there can be n number of `[variable]` in the given string.

I tried many ways but no luck.