Use the TRIM function: `=TRIM(A1)`
Copy the formula down for the rest of the cells
Copy the results
Paste Special as Values to replace the original text
Use Find and Replace to remove extra spaces manually
Select the range
Press Ctrl+H
Find what: enter two spaces
Replace with: enter one space
Click Replace All
Repeat until no extra spaces remain
Use CLEAN to remove non-printing characters: `=CLEAN(A1)`
Combine CLEAN and TRIM: `=TRIM(CLEAN(A1))`
Use Flash Fill if the pattern is simple
Use Power Query to trim and clean columns
Use VBA if you need to process many cells automatically