Current fossil fuel subsidies are included in the En-ROADS Baseline Scenario, and you can remove them by moving the coal, oil, and natural gas sliders to "taxed." 

“Taxing” here implies the removal of these subsidies by increasing the cost. In En-ROADS, we use the word “tax” to encompass any action making the energy source more expensive. This does not necessarily have to be a direct government tax; it could include such things as divestment movements, private sector decisions, removal of subsidies, etc.

Fossil fuel subsidies are government actions that lower the price of fossil fuels, for instance by lowering the price paid by consumers or decreasing the cost of producing fossil fuels. The estimates for current subsidies are large and varied.

Here is one way to simulate removing fossil fuel subsidies in En-ROADS:

The International Monetary Fund estimated explicit fossil fuel subsidies in 2022 to total around $1.3 trillion. A negative subsidy (i.e., a tax) of $45/tce on coal, $40/boe on oil, and $2.2/Mcf on natural gas would amount to $1.3 trillion in 2030. See this scenario in En-ROADS.