Deprecation — in other words, signaling that a function is becoming obsolete in the near future — is necessary for the web ecosystem. Features are updated or replaced with newer APIs, and must be removed in order to foster growth on the web. Deprecation is the precursor step to feature removal; these two functions are tightly coupled, as a successful deprecation leads to a successful removal. However, an unsuccessful deprecation can lead to pain for both developers and end-users. While Chrome has a protocol for web feature deprecation, much of this process is based on a mix of few metrics and intuition. In this paper, we analyze web feature deprecations, in an attempt to improve this process by balancing the need for deprecation and minimizing user pain. First, we produce a taxonomy of reasons why developers want to deprecate web features. We then provide a set of guidelines for helping to decide when it is safe to deprecate a web feature and a methodology for approaching the question of whether to deprecate a web feature. Finally, we provide a tool that helps determine whether a web feature meets these guidelines for deprecation. We also discuss the challenges faced during this process.