Remove Duplicates Letters

With the use of functions and loops this can be achieved. First you need to split the text into a character array. Then remove the duplicates from the character array. Result will have unique characters - uppercase and lowercase will be in this array as they are unique still! Lastly we identify/reject the duplicates doing a case match and return the output as expected, in the same case and order as present in original text.

Below is a code with the solution for this interesting question. Hope it helps! 

a!localVariables(
  local!text: "Deleted",
  local!charArray: a!foreach(
    enumerate(len(local!text)) + 1,
    local!text[fv!item]
  ),
  local!unique: union(local!charArray, local!charArray),
  joinarray(
    a!foreach(
      local!unique,
      if(
        fv!isFirst = 1,
        fv!item,
        if(
          length(
            wherecontains(lower(fv!item), lower(local!unique))
          ) > 1,
          {},
          fv!item
        )
      )
    )
  )
)

With the use of functions and loops this can be achieved. First you need to split the text into a character array. Then remove the duplicates from the character array. Result will have unique characters - uppercase and lowercase will be in this array as they are unique still! Lastly we identify/reject the duplicates doing a case match and return the output as expected, in the same case and order as present in original text.

Below is a code with the solution for this interesting question. Hope it helps! 

a!localVariables(
  local!text: "Deleted",
  local!charArray: a!foreach(
    enumerate(len(local!text)) + 1,
    local!text[fv!item]
  ),
  local!unique: union(local!charArray, local!charArray),
  joinarray(
    a!foreach(
      local!unique,
      if(
        fv!isFirst = 1,
        fv!item,
        if(
          length(
            wherecontains(lower(fv!item), lower(local!unique))
          ) > 1,
          {},
          fv!item
        )
      )
    )
  )
)