Reducing Table Size in OS – Need Advice

We're trying to reduce the size of a large table in OS (about 650GB). Our initial idea was to copy the rows to a new table and then rename it, but the insert process takes too long due to the size and ends up timing out. Deleting records from the table itself seems risky and take's similar duration. 

Has anyone dealt with something similar? Would appreciate any tips or suggestions for a faster and more efficient approach. Thank you!