First off, welcome to the site. Next, It sounds to me like you did alright, you hardly ever see many of those machines for sale plus you got a trailer and the box blade. The first thing you should do is call your closest Kubota dealer and get yourself an owners manual so you know all the correct service intervals and it also explains in detail how to remove the hoe.
I had an
L35 and I believe the hoe attaches the same way on your machine so I'll do my best to talk you through.... Get the machine on solid ground and as level as possible, lower the front bucket to the ground, turn around and kneel on the seat so you are facing the hoe, keeping the hoe in the "transport" position (I mean just as you would if you were using the loader end of the machine)lower it to the ground slowly using only the boom of the hoe, once the back of the bucket linkage touches the ground apply just enough pressure to lift the rear wheels off the ground, now there should be two levers located just behind where your feet would sit if you were running the hoe(it may be easier to get off the machine at this point ), follow them down to the base and there should be a hair pin clip that stops you from accidently releasing the lever while using the hoe, while gently wiggling the lever remove the clip and pull the lever back, this will release the locking cam that holds the top of the hoe to the frame, and you should be able to see another hole for the clip to go into that will keep the lever disengaged, do the same on the other side. If the hoe has never been off the cams may be rusted or stuck, so have some penetrating oil near by just in case. Now get back on the machine and face the hoe again while kneeling on the seat, very slowly, raise the boom and this will cause the hoe to "fall away" from the machine (be sure to watch the hydraulic lines while doing this, make sure they are not tangled on anything and that they can move freely,if they get hung up they will break and it'll be a big mess) keep lowering the boom until it stops, now lower your stabilizers to the ground SLOWLY, this will lift the hoe out of the lower framework, you must now, very carefully and very slowly(I can't stress that enough) drive the machine ahead(again watching out for the hydraulic lines) about 6", this will get the machine out of the way and allow you to turn around in the seat and slowly raise the stabilizers so that the frame rests on the ground, now shut the machine off and wiggle the joysticks on the hoe to relieve any residual hydraulic pressure, now you can disconnect the hydraulic lines from the machine to the hoe and the hoe to the machine and reconnect them, machine to machine and hoe to hoe(it is VREY important that the lines are securely connected before restaring the machine).Now your hoe is disconnected ,and you are ready to install the three point hitch. This is alot of info to take in but don't be intimidated by it, just take your time and be patient,once you get the hang of it you should be able to remove the hoe in under two minutes, hope this helps.