indent-rigidly

indent-rigidly is an interactive compiled Lisp function in `indent.el'.

It is bound to C-x TAB.

(indent-rigidly START END ARG &optional INTERACTIVE)

Indent all lines starting in the region.
If called interactively with no prefix argument, activate a
transient mode in which the indentation can be adjusted interactively
by typing <left>, <right>, <S-left>, or <S-right>.
Typing any other key deactivates the transient mode.

If called from a program, or interactively with prefix ARG,
indent all lines starting in the region forward by ARG columns.
If called from a program, START and END specify the beginning and
end of the text to act on, in place of the region.

Negative values of ARG indent backward, so you can remove all
indentation by specifying a large negative ARG.