Vertex deletion to the hereditary graph class has been well-studied in parameterized complexity. Vertex deletion in scattered graph classes has attracted attention in recent years. In this paper, we consider (PROPER-INTERVAL, TREE)-VERTEX DELETION, the input to which is an undirected graph $G = (V, E)$ and an integer $k$. The goal is to pick a set $X \subseteq V(G)$ with at most $k$ vertices such that $G - X$ is a simple graph and every connected component of $G - X$ is a proper interval graph or a tree. When parameterized by the solution size $k$, (PROPER-INTERVAL, TREE)-VERTEX DELETION has been proved to be fixed-parameter tractable by Jacob et al. [JCSS-2023, FCT-2021]. Notably, (PROPER-INTERVAL, TREE)-VERTEX DELETION is a natural and substantial generalization of (CLIQUE, TREE)-VERTEX DELETION, which has been explored recently [JCSS-2026, ISAAC-2025, IPL-2025, ISAAC-2024]. The kernelization techniques for the latter exploit the finite forbidden induced subgraph characterization of cliques. In contrast, proper interval graphs and trees admit infinite forbidden induced subgraph characterizations, requiring new structural arguments. In this paper, we consider this problem from the perspective of polynomial kernelization and provide the first nontrivial polynomial kernel for (PROPER-INTERVAL, TREE)-VERTEX DELETION, with $O(k^{33})$ vertices.

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