Commuting: How to carry office clothing so it doesn't get crushed?
You have two options, essentially: You can either carry each day's clothing on every trip, or store clothing at work. 

Carrying clothing daily

If you're going to do this, you'll need to find a way to roll up your clothing so it's not completely wrinkled. Be aware that even packing clothing in the most wrinkle-free way possible will still not keep it as fresh-looking as when you pull it out of the closet. 

Many business travelers have found that the best way to transport clothing is to roll it. Do some searching, not on bike sites, but on business sites, and you'll find videos that get into this in more detail. But the gist: Fold along seams, then roll your clothing. The parts that must be least wrinkled (shirt collar, for example) should remain on the outside. You can also experiment with rolling around a towel, leaving some extra towel at the end and then rolling that around the bundle. This will become your clean-up towel at work. 

As you're showering at work (or taking a sink bath), hang your clothing up and let it hang up a bit. Allow a little extra time for this. 

It's worth noting at this point that many people continue to sweat even after they stop exercising, so you may want to wait ten to fifteen minutes before showering. (Riding gently for the last mile or three can also help.) 

There are special cases that hold clothes, but they all (to my knowledge) involve folding them. I think that this will invariably crease the clothing. 

Storing clothing at work

If you have a spare closet or other space where you can leave clothing hanging at work, this is a great option. Consider doing a half-commute on Mondays, carrying the bike and clothing in, then riding home. On Friday, reverse the process. 

If you have a space like this, you can also leave shoes there, and possibly even a travel iron for touching up clothes (if you want to look particularly sharp). 

You might consider leaving a spare outfit at work in any case. I always worried that I would forget, say, underwear, or a belt, so I left an older set of clothing in my locker. 

If your work doesn't have a space like this, look into nearby gyms. Some gyms will let you use the showers and locker room for a small fee, one that's smaller than a gym membership. Some larger businesses even have gyms on-site for employees. 



It's worth noting that commutes of a mile or two may not require changing at all, but you'll still have these things to deal with in very hot or cold weather, or when riding in the rain. (Edit: Your 6k commute is a bit long for this, but it's still good advice in general.)

Best of luck on the commute! Speaking from personal experience, I recommend allowing a lot of extra time the first few commutes, and also doing a dry run of the route (if you haven't already). Also consider talking to any cycling co-workers: Some of them may have solved the problems related to your specific workplace.