Step 1: Decide which character you need to format.

Step 2: Use an empty column to start writing your formula.

Step 3: Use the following formula to remove everything after (and including) the specified character:

=LEFT(Cell, FIND(":", Cell) - 1)

Step 4: Copy the newly formatted data and Paste as Values to retain the results without the formula.

Example:

We want to keep only "CABLE TERMINATION" from the following:
CABLE TERMINATION: Glands, Terminals, Lugs, Links & Connectors

Formula Applied in Cell A2:

=LEFT(A1, FIND(":", A1) - 1)