Smith & Wesson made several different pistols in .45 ACP, including an M1911 pattern pistol. You'd have to be more specific about which model you had in mind before this question could be answered, as the different models vary quite a bit.
You can request a manual at the Smith and Wesson web site.
Best left to a trained gunsmith
Ask a gunsmith for help
have a gunsmith show you. less chance of damage.
Best to ask a gunsmith for help. Various models and not all strip the same.
You can request an owner's manual for free at the S&W website.
You can request a manual on the S&W website. You can ask a gunsmith for help.
Contact S&W and ask for a manual or find a gunsmith and ask for help.
Knowing the model would help a little, but in general, you field strip it, put some solvent on it, let it sit a few minutes, wipe the solvent off, lube it, reassemble it. That's a very basic description.
Best left to a trained gunsmith.
To field strip a Smith & Wesson 639, first ensure the firearm is unloaded. Remove the magazine and pull the slide back slightly to align the takedown lever with the notch in the slide, then rotate the takedown lever down. With the lever down, pull the slide off the frame while holding the trigger slightly to release tension. Finally, remove the recoil spring and barrel from the slide for further cleaning or maintenance.
Follow the instructions in the owner's manual.