delete field (column) from a list powershell, error Collection has been modified

Question

following is my code:

foreach($field in $list.Fields)
{
    if($field.StaticName -eq "temp1" -or $field.StaticName -eq "temp2")
     { 
         if($field.Id -ne $depId)
         {
             $field.AllowDeletion = $true
             $field.Delete()
             $list.Update()
         }
     }
     else 
     {
         if($field.StaticName -eq "notActive" -and $field.Id -ne $aktId)
         {
              $field.AllowDeletion = $true
              $field.Delete()
              $list.Update()
         }
     }
  }

but it generates, Collection was modified; enumeration operation may not execute.

Answer 1

You can not modify size of collection that is used by foreach operator. You can save ids of field that should be deleted then loop through the ids, find this field in field collection by id and remove it.