1) disable steam cloud
2) keep removing the backup file before you close game, it will halve the space taken in cloud
3) you mean world or character?
if world then I think there is no way
if character then just make new character and move all items onto it (maybe cheat the skills too and screenshot the map)

why?
because map is saved on character
each world has separate map
so each world you visit has map saved on your character (well, when it's not explored it takes small bit of space because it's optimized) but if you cheat command "exploremap" on multiple worlds then character size is going to explode

Originally posted by ec928:

where you got the 150 figure.

No idea how it looks in english version of steam... but in polish language steam poorly displays size of cloud ;D

my valheim has 950MB steam cloud
steam displays it as "taken: 50MB / avaible: 900MB"
this "avaible" part might be confused as "max" because of the "/"
it doesn't specify whether it's remaining avaible or max avaible so the "/" makes important mark there

usually max is on the right side of "/" when you display numbers