No you dont remove FPC 2.6 once its installed infact install in this order :
Install FPC 2.6
Install FPC 2.6 Src
Finally Install Lazarus 1.0.4
but make sure before you do you have cleaned up and removed all
other lazarus versions and FPC 2.4 etc
Lazarus has to have FPC binary installed, since Lazarus is just a Frontend GUI
for FPC. Lazarus without FPC is just a Useless GUI .
So im thinking perhaps the install instructions your reading are misleading your
install order.
If you dont have synaptic installed open a terminal and type:
sudo apt-get install synaptic
once installed type
gksudo synaptic
once synaptic is done rebuilding search index do update, make sure there
is no broken dependency. and finally search for fpc 2.4 and dependency and remove them,
same for lazarus older versions , make sure no lazarus or fpc is installed at this point, make
through search. Once your satisfied, so we will need to drop to terminal again. And remove
all directory's pertaining to Lazarus, and FPC once this is done we will Install FPC 2.6 then
the Src Package for FPC 2.6 and Finally install Lazarus 1.0.4.
So open terminal and type
gksudo nautilus
This will open a new window in nautilus explorer as a root user, so we can remove all existing directories
for old version of FPC and Lazarus. We do this before installing Upgrades.
Now we will need to search for in root and top side directory by opening Accessories / Search for files, make sure / is selected for search path. type in fpc the the path to all links binary etc for fpc then use the root nautilus explorer to remove them, wash rinse and repeat for Lazarus , once done perform the new install
when it tells you and older version is in respo ignore and continue install .
All should be well after this process