Did you read the owners manual ?
Front & back deck lifts are held on with clevises so you just remove the pins
Latter deck looks like it has a tie rod end held on with a nut .
Did you own this mower from new or get it second hand cheap ?
Some one whose tool box contains only an angle grinder & welder could have repaired it in the past.

From what I can see the nuts all marked #4 get removed and then the rear lift arms should slide out from the deck side
If not then the keyrings marked # 18 come off to allow the lift arms to be removed from the mower side but the nuts on the droppers # 12 still have to come off to release the deck
Usually you need to put some 2x4's under the mower deck to make sure there is no weight on the lift arms.
Use some long ones then you san slide the deck out on them using then as rails .
Otherwise without the deck weight it is easy to lift the front of the mower & roll it back out of the way
The other version uses clevises rather than ball ended tie rod ends in which case to take the keyring retainers out as above and then the nuts holding # 12 in place
If it is difficult yo get in to remove the keyrings they can be cut off & replaced with bowtie clips, R clips , split pins or even a bent nail