Question: How do I use regex to convert 

```
11111aA$xx1111xxdj$%%`

```

to 

```
aA$xx1111xxdj$%%

```

So, in other words, I want to remove (or match) the FIRST grouping of `1`'s.

Answer: 
If this is the beginning, you can use this:

```
^[1]*

```

As far as replacing, it depends on the language. In powershell, I would do this:

```
[regex]::Replace("11111aA$xx1111xxdj$%%","^[1]*","")

```

This will return:

```
aA$xx1111xxdj$%%

```
If you only want to replace consecutive "1"s at the beginning of the string, replace the following with an empty string:

```
^1+

```

If the consecutive "1"s won't necessarily be the first characters in the string (but you still only want to replace one group), replace the following with the contents of the first capture group (usually `\1` or `$1`):

```
1+(.*)

```

Note that this is only necessary if you only have a "replace all" capability available to you, but most regex implementations also provide a way to replace only one instance of a match, in which case you could just replace `1+` with an empty string.