Move cells to the left

Move cell contents to the left side in columns D, E, F, G. (Phone numbers)
So let’s say that a cell on column D is empty and but the cell to the right E has a phone number i would like to have the number on the cell of column D
So basically within the columns D, E, F, and G. i want all the phone number to the left without affecting any other columns.
Any help with this I appreciated
I also attach a sample spreadsheet for better understanding Thankyou

Cut columns D:G and paste them into columns M:P.
With columns M:P still selected press F5 > Special > Blanks > OK.
Right click > Delete > Shift Cells Left
Cut columns M:P and insert them back into D:G again.