One of my favorite things about Sublime Text 2 (along with great
Python and Ruby support) is the fast project switching. This is accessed via the
super+ctrl+p keyboard shortcut by default. The only problem with this, is
after a while the list can become polluted. The only solution provided by
Sublime Text is to clear all items:

However if you are willing to open a couple of config files, you can clean out the specific unwanted projects and maintain quick access to all your wanted projects. How this is done was not immediately obvious to me so here are the steps.
Step 1: Locate your Sublime Text 2 Data Folder
By default these are:
- OSX:
~/Library/Application Support/Sublime Text 2 - WINDOWS:
%APPDATA%\Sublime Text 2 - LINUX:
~/.config/sublime-text-2
The other steps will refer to everything relational to this folder.
Step 2: Locate the .sublime_settings Files
Typically it seems there are two of these located in ./Settings.
$ find . -name "*.sublime_session"
./Settings/Auto Save Session.sublime_session
./Settings/Session.sublime_session
Step 3: Remove unwanted projects
Each of these .sublime_session files is a JSON formatted file. In each
file, find the workspaces.recent_workspaces array. It should look something
like this:
{
"... Rest of Session Data ...",
"workspaces":
{
"recent_workspaces":
[
"/Users/jwebb/src/project_a/project_a.sublime-project",
"/Users/jwebb/src/project_b/project_b.sublime-project",
"/Users/jwebb/src/project_unwanted/project_unwanted.sublime-project",
]
}
}
Simply delete the offending project from each file:
{
"... Rest of Session Data ...",
"workspaces":
{
"recent_workspaces":
[
"/Users/jwebb/src/project_a/project_a.sublime-project",
"/Users/jwebb/src/project_b/project_b.sublime-project"
]
}
}
Step 4: Save changes and Restart Sublime Text
Be sure that you still have valid JSON (trailing commas in the correct places etc) and then restart Sublime Text.