Forgetting, which has also been studied under the names uniform interpolation, projection and variable elimination, deals with the elimination of symbols from an input ontology in such a way that all entailments in the remaining signature are preserved. The computed result, the uniform interpolant, can be seen as a restricted view of the original ontology, projected to a specified subset of the signature. Forgetting has applications in ontology reuse, ontology analysis and information hiding, and has been studied for a variety of description logics in the last years. However, forgetting in description logics with functional role restrictions and inverse roles has been an open problem so far. In this paper, we study the problem of forgetting concept symbols in the description logic SIF, an expressive description logic supporting transitive roles, inverse roles and functional role restrictions. Saturation-based reasoning has been proven to be a well-suited technique for computing uniform interpolants practically in recently introduced methods. Since existing methods are usually optimised towards a specific aim such as satisfiability checking or classification, they cannot always directly be used for forgetting. In this paper we present a new saturation technique that is complete for forgetting concept symbols, and show how it can be used for computing uniform interpolants.