Alternative to hot-patch the backdoor in the E2Power addon; https://github.com/VelaEurope/E2Power/pull/7

Remove-E2Power-Backdoor.lua

-- Hot-patch the backdoor in the E2Power addon.
-- Place this in your server's autorun Lua.

if not (SERVER and file.Exists('entities/gmod_wire_expression2/core/custom/E2Power.lua', 'LUA')) then return end
-- Only run this if E2Power is installed.
local rawset, pairs, getinfo, getupvalue = rawset, pairs, debug.getinfo, debug.getupvalue
local function get_upvalues(func)
    local info = getinfo(func, 'u')
    if info then
        local variables = {}
        for i = 1, info.nups do rawset(variables, getupvalue(func, i)) end
        return variables
    end
end
local hook_GetTable, hook_Remove, timer_Simple, remove_backdoor = hook.GetTable, hook.Remove, timer.Simple
function remove_backdoor()
    if E2Power then -- Wait for E2Power to load.
        local hooks = hook_GetTable()
        hooks = hooks['PlayerInitialSpawn']
        if hooks then
            local first, second = hooks['E2P_runlua'], hooks['E2Power_CheckPlayer']
            if first and second then -- Wait for both hooks to be found.
                -- Remove the backdoor.
                for name, value in pairs(get_upvalues(first)) do
                    if name == 'WhiteList' then -- Clear the whitelist table.
                        for k in pairs(value) do rawset(value, k, nil) end
                        break
                    end
                end
                for name, value in pairs(get_upvalues(second)) do
                    if name == 'WhiteList' then -- Clear the whitelist table.
                        for k in pairs(value) do rawset(value, k, nil) end
                        break
                    end
                end
                hook_Remove('PlayerInitialSpawn', 'E2P_runlua') -- Finally, remove the useless hook.
                --hook_Remove('PlayerInitialSpawn', 'E2Power_CheckPlayer')
                return -- Done. Exit the loop.
            end
        end
    end
    timer_Simple(1, remove_backdoor) -- Keep looping until removed.
end
timer_Simple(10, remove_backdoor) -- Start the loop.