Enable Validator in Email in arabic DisplayName

To Create formula validation for fields in arabic display name you needto replace all commas ',' with semicolons ';'

Check below Email Formula validation  for Arabic field:

=AND(ISERROR(FIND(" ";[البريد الالكترونى];1));IF(ISERROR(FIND("@";[البريد الالكترونى];2));FALSE;AND(ISERROR(FIND("@";[البريد الالكترونى];FIND("@";[البريد

الالكترونى];2)+1));IF(ISERROR(FIND(".";[البريد الالكترونى];FIND("@";[البريد الالكترونى];2)+2));FALSE;FIND(".";[البريد الالكترونى];FIND("@";[البريد الالكترونى];2)+2)
الالكترونى])))))

Cannot delete Column from List

When tried to delete some columns from list using GUI, Some of them don't give me option to delete.
Problem: I Can't delete column if it is sealed, hidden, or readonly
Solution: Change values of these properties to false before trying to delete

You can use PowerShell to change these properties and remove column from List like below:
$web = Get-SPWeb -identity SiteUrl
$list = $web.Lists[listName]
$column = $list.Fields[FieldName]
$column.Sealed = $false
$column.Hidden = $false
$column.ReadOnlyField = $false
$column.Update()
$list.Fields.Delete($column)