Tilt, Flip, and Rotate Individual Letters in Photoshop
Photoshop’s standard transform commands rotate or flip entire words when the text is still editable type. To work on individual letters, first convert the text to shapes. Then you can select any letter and flip, rotate, and even change the rotation pivot without affecting the rest of the word.

Step-by-step instructions
Prepare your text and know the limitation
Select your type layer in the Layers panel.
Note: Edit → Transform on live type affects the entire word; to edit letters individually, convert the text to shapes.
Convert the text to shapes
With the type layer active, go to Type → Convert to Shape.
Confirm the layer is now a shape layer (path icon in the thumbnail).
Select a single letter
Choose the Path Selection Tool (black arrow) in the toolbar (not the white Direct Selection Tool).
Click away from the word to deselect all, then click a letter to select it (its anchor points will appear).
Flip one letter
Right-click (Control-click on Mac) and choose Free Transform Path.
Right-click again and choose Flip Horizontal or Flip Vertical, then click the checkmark or press Enter/Return to apply.
Click away to deselect if needed.
Rotate one letter
With the letter selected, press Ctrl+T (Windows) or Command+T (Mac).
Drag outside the box to rotate; hold Shift to snap in 15° increments.
Press Enter/Return to apply, then Enter/Return again to deselect.
Change the rotation pivot (optional)
In the Options bar, enable Show Reference Point to display the pivot target.
Drag the target to a new pivot (e.g., a corner handle) and rotate as desired.
Drag the pivot back to the center when finished for standard rotations.